This suspect may be a bit out of the left field, but honestly I'm completely on board with this. Regenerator needs to go.
I. Regenerator as a broken trait
To put it bluntly, Regenerator is absurdly strong. In an otherwise highly offensive metagame, the degree to which it skews risk vs reward by boosting an already useful action in switching with a significant healing effect often draws out many games for far longer than necessary. It's not hard to see just how effective Regenerator is - despite its relatively limited distribution, three of its users in Mienfoo, Foongus, and Mareanie rank among the very best Pokemon in the metagame, with Slowpoke being a high tier Pokemon as well; only Solosis remains relatively unviable, but not even Huge Power could salvage such a poor stat distribution and movepool. I'll talk more about how the four noteworthy Regenerator abusers are individually so strong later in the post.
I'd like to go into more detail on the risk vs reward aspect of Regenerator here by comparing it to one of the more popular pro-Diglett ban arguments. The claim is that by completely preventing switching once it's in play, Diglett affects decisions based on risk vs reward to an extreme degree simply by being present on the opposing team. Plays that would otherwise be perfectly acceptable in a non-Diglett game, such as switching into a VoltTurner or even KOing a weakened Pokemon, can become poor choices if your Pokemon is weak to Diglett and you need it for something else on their team, as Diglett's ability allows it to almost guarantee that your Pokemon is removed afterwards. Repeatedly clicking VoltTurn to deal a slight amount of chip, and maintaining weakened Pokemon to sack, are two actions that become hugely more powerful if you have a Diglett to get into play through these means.
With that being said, I'm personally anti-ban for Diglett, and my counterargument for that pro-ban argument in particular is that this aspect of risk vs reward is something that both players can take into consideration at any point in the game. You can take into account that Diglett will be able to take out your Pokemon if you come in on a well-timed U-turn or KO a sack, and decide whether or not what you have to gain from coming in anyways is worth the tradeoff of possibly losing your Pokemon to Diglett. Factoring into this decision is that while being able to take advantage of VoltTurn and sacks to such an extent is certainly enough to rank Diglett as one of the top Pokemon in LC, the amount of momentum it loses after completing a revenge-kill is still a very notable tradeoff; the fact that Diglett relies almost solely upon Earthquake to deal damage, and that its Earthquake isn't even that strong when not boosted by Groundium Z, means that a number of the most threatening Pokemon in the metagame, including Vullaby and Snivy, are able to get into play for free, which can often be just as rewarding as what the Diglett user gains from trapping its target. In short, while Diglett does skew risk vs reward, I feel that it doesn't do so in a manner that actually favours the Diglett user to a broken extent - it merely adds another layer to what both players have to account for.
Now, what does this have to do with Regenerator? The issue here is that Regenerator skews risk vs reward in the exact opposite direction of Diglett; instead of preventing switching, it makes switching too strong. Because leftovers isn't viable, it's obvious that chip damage is strong in LC. However, chip damage is actually much more than that - it's an integral part of why our metagame is balanced despite the fact that we have both Eviolite and Berry Juice. I'm not arguing that these items should be banned - otherwise, we'll likely end up with a rather luck-based metagame similar to DPP LC, made even worse due to the presence of Z moves, and have no way to get out of such a metagame state, which is of course far from ideal. My point is that every single Pokemon in the tier has access to these enormously effective defensive items that level 100 tiers really have nothing close to. By being able to gradually wear these Pokemon down in conjunction with smart plays to pressure them from healing, we have nevertheless been able to create a fun, offensive metagame that, while obviously not being anywhere close to luck-free, is still relatively skillful compared to other metagames. By negating chip damage, Regenerator just about completely throws this out the window.
Let's take a look at my counterarguments for the Diglett-banning argument I described above. For Diglett, I mentioned that risk vs reward wasn't actually skewed against one player in particular. In Regenerator's case, it most certainly is, as it causes certain actions to simply not have any effect in the long run. Without the right Pokemon on your team, Regenerator Pokemon aren't just difficult to break through in the way that you might be put on the back foot against Shellder or Vullaby if you're not prepared for them; they're flat out impossible to take out without significant amounts of luck. No amount of momentum to deny healing moves will save you from having them heal a third of their health just by switching out. This may be less of a concern in other tiers where the key walls tend to be passive enough to be taken advantage of by threatening wall-breakers, but in a metagame like LC that heavily emphasizes maintaining momentum, being hard walled is a huge no-no. As a result, Pokemon that are unable to break through the most popular Regenerator abusers tend to fall into obscurity. For example, without Mienfoo's presence, Munchlax would likely be fairly good, though not amazing, but with Mienfoo, it is almost never seriously considered on a competitive team; and despite having several enormous perks and being fantastic for role compression, defensive Tirtouga isn't even one of the top 20 best Pokemon in LC.
Furthermore, every major Regenerator abuser is very threatening in its own right almost entirely due to Regenerator - while Foongus or Mareanie wouldn't be too viable without Regenerator, they become an extremely potent combination of both difficult to KO and difficult to take advantage of with it. Diglett is a rather poor choice without Arena Trap, and because of this, using Diglett isn't for free - you need a great deal of support to take advantage of Diglett's support through VoltTurn and sacks. However, it'd still likely be more viable than a Regenerator-less Foongus, as Spore alone would not be enough to mitigate Foongus's otherwise underwhelming movepool and stats. Arena Trap may bolster Diglett's viability tremendously, but it doesn't completely eliminate counterplay. Regenerator, on the other hand, does so undoubtedly, and as a result, increases the viability of its users to a far greater extent; their otherwise mediocre strengths are increased so drastically that they can completely get around any disadvantages that their weaknesses might otherwise cause. Items are relatively balanced by how all of the best ones (Eviolite, Berry Juice, Life Orb, Choice Scarf) are substantially stronger in LC than at level 100 because of how stats at level 5 are calculated, meaning there is a significant drawback to using one extremely strong item, in being unable to use the other extremely strong items. Regenerator has no such inhibition - it is a stronger ability than most, causing its users to rely on it to a much greater degree, and has a far better distribution than comparably effective abilities.
What makes a given trait broken? The
tiering policy framework states these to be ''elements that are too good relative to the rest of the metagame such that "more skillful play" is almost always rendered irrelevant'', going on to say that broken traits ''aren't necessarily completely uncompetitive because they don't take the determining factor out of the player's hands; both can use these elements and both probably have a fair chance to win. They are broken because they almost dictate / require usage, and a standard team without one of them facing a standard team with one of them would be at a drastic disadvantage.'' This, I feel, applies to a significant extent to both Mienfoo and Foongus. While it isn't outright impossible to build a solid team without a single Regenerator Pokemon, any team will automatically have holes opened in them that aren't straight forward to patch if they aren't included; you are putting yourself at a significant disadvantage that takes an enormous amount of difficulty in the teambuilding stage to effectively remedy, and for just about no gain. This is especially noticeable in tours, where Mienfoo in particular sees ridiculously high usage compared to every other legal Pokemon - it's outright more difficult to build a team without Mienfoo than with one.
II. Potentially broken Regenerator abusers
Now let's take a closer look at each Regenerator abuser, and why Regenerator either pushes them well over the edge or allows them to dance worryingly close to it.
Mienfoo
Since its introduction in BW, Mienfoo has ranked as one of the very most splashable and metagame-defining Pokemon in its respective metagames; while it shares its throne in both of these categories with Misdreavus in BW, it stands uncontested at the very top in SM, ORAS, and late XY. In terms of sheer metagame influence, no other Pokemon in LC can even approach Mienfoo. Its closest competition, Diglett, owes a large portion of its viability to Mienfoo, the most reliable and reusable way to get Diglett into play safely; it's generally quite rare to see Diglett being used without Mienfoo on the best and most consistent teams due to Diglett's lack of reliability without it. There's also the fact that Mienfoo has flat out shaped the metagame more than Diglett has - simply being a Mienfoo answer counts as a niche, and surprisingly enough, being weak to Mienfoo actually seems to be more damaging to a Pokemon's splashability and overall viability than being weak to Diglett (compare Normal-types like Lickitung and Munchlax to Poison-types like Foongus and Mareanie, for example).
Every metagame will have its best Pokemon, of course, so that alone isn't a reason to ban a Pokemon. The reason that Mienfoo is worrisome here is that it stands head and shoulders above the rest of the metagame, and has done so consistently for years. The other S ranks in Diglett, Foongus, and Vullaby may be able to compete in terms of raw effectiveness, but they can't even come close in terms of splashability - it's arguably easier to include Mienfoo on a team than to not do so, and the usage stats show it. Mienfoo is simply so reliable at what it does, can be tailored to fit so many teams, and has so few exploitable weaknesses, that several of the top LCers of today weren't even born the last time it was ranked somewhere other than first on every relevant usage list. While it may be difficult to see Mienfoo as outright broken at first due to the passive playstyle of its most popular set, the Eviolite pivot, but Mienfoo drastically limits diversity in LC in multiple respects on top of toeing the line in terms of strength.
Eviolite Mienfoo is quite possibly the single most dominant set on any Pokemon in LC, with defensive Foongus, Tectonic Rage Diglett, and pivot Vullaby competing for second. EV spreads can be tweaked here - defensive fastfoo (196 Def / 36 SpD / 236 Spe Jolly) and defensive slowfoo (156 HP / 116 Def / 196 SpD Impish) are the most common variants, but there is plenty of room to increase Attack and get more KOs with High Jump Kick, or increase its HP to 24 to hit a Regenerator number. If you look at Mienfoo's defensive stats, though, they aren't actually very impressive, so why is its most prominent set a defensive one? Simply put, Eviolite Mienfoo owes almost the entirety of its viability to Regenerator. In conjunction with its resistance to Stealth Rock, Mienfoo is deceptively difficult to wear down, allowing it to come in repeatedly to spread Knock Offs and get off safe U-turns. The biggest thing to take away here is that Regenerator makes it far too reliable and consistent a U-turn pivot, making U-turn ridiculously low risk for a potentially enormously reward. Many of the tier's suspected and/or banned offensive Pokemon were only so strong because of Mienfoo's presence - the likes of Torchic, Conversion Porygon (not too bulky without Eviolite), Diglett, and Scarf Gothita all struggled badly to get into play without Mienfoo's aid throughout the match. Its other sets, while good, are nowhere near as prevalent as Eviolite Mienfoo, and in fact owe a large portion of their viability to Eviolite Mienfoo being so common - they often need to take advantage of the opponent assuming an Eviolite set, both while teambuilding and during the actual battle, to succeed.
Now, unlike the other Regenerator users I've listed here, Mienfoo would likely maintain a niche even without Regenerator; its Eviolite set is the only one that truly relies on its ability. Choice Scarf and Life Orb variants often run Regenerator as well, as it is quite helpful to mitigate High Jump Kick misses and generally increase longevity, but they would still be able to make do without it; in fact, Reckless variants of Choice Scarf Mienfoo are just as common as Regenerator variants. Choice Band Reckless Mienfoo has incredible immediate power that allows it to act as a potent wall-breaker. Flyinium Z Mienfoo can act as an effective lure for several important threats, but it is most commonly used for, surprise surprise, Foongus and opposing Mienfoo. Of course, these offensive sets would be noticeably less effective without the Regenerator sets to give them surprise value, but they would still be quite strong on the right teams; notably, Mienfoo has more bulk and immediate power than the only other Fighting-type with U-turn, Mankey, so it would likely continue to perform well on Fighting spam teams. However, there's no question that Mienfoo would drop out of S and even A without Regenerator, as at the end of the day, its Eviolite pivot set is its most notable set, and the reason why it's so difficult to give up. If we get rid of Regenerator, Mienfoo would be downgraded from the single most metagame-warping Pokemon in the tier to a decent Pokemon with a decent niche.
Foongus
Mienfoo may be the most splashable Pokemon in LC, but the title of most broken Pokemon in LC unquestionably belongs to Foongus. Between Spore, a good defensive typing, and above all Regenerator, Foongus cannot be stopped. This is especially true in the current metagame where the sole relevant hard check to all common Foongus variants, Overcoat Vullaby, is on the decline and largely in disuse outside of Choice Scarf variants, which take a large amount from Sludge Bomb. For a large portion of teams, their Foongus answer is simply their own Foongus; this isn't due to a lack of preparation or poor building habits, but rather that Foongus is simply too difficult to check otherwise. A Foongus of your own is far stronger in most matchups than other Foongus answers, and gives you some room to work around the opposing Foongus and get a Fire- or Flying-type or a Tectonic Rage Diglett into play.
Simply put, the LC metagame has become highly Foongus-centric. If you don't have a Foongus on your team, then you have to either build your team such that you have multiple Foongus soft checks and lures to ensure that you aren't weak to it to begin with, or an otherwise generally unviable Foongus hard check to not lose to it, thanks to a well-timed Spore taking out one potential Foongus check and Regenerator allowing Foongus to easily outlast the remaining opposition. This often opens up far more holes and puts you at a disadvantage against other teams, meaning it's usually better to just use a Foongus of your own. Despite being a passive and defensive Pokemon, Foongus will frequently find itself acting as the win condition late game due to it being far healthier than everything else. In fact, you'll find that in the vast majority of games, if one team manages to remove the opposing Foongus while keeping their own Foongus healthy and with an intact Eviolite, then the match has already been decided.
This can be seen in the choice for Foongus's filler move that has become so popular recently, Synthesis. Even though it forces Foongus to give up a useful Hidden Power for coverage or Clear Smog to better check certain sweepers, Synthesis is generally considered the best choice for a filler move right now. Hidden Power Fire and Fighting are still occasionally used for Ferroseed and Pawniard, respectively, but at this point, you can almost always expect Synthesis from the get-go. Why is that? Synthesis does help in other regards, such as helping Foongus outlast Fighting-types, mainly Mienfoo, with even more ease, but the main reason is to help with Foongus mirror matchups; an Eviolite Foongus with Synthesis will always beat an Eviolite Foongus without Synthesis. That's right - in a metagame where Foongus could use its last slot to defeat some top offensive threats with Hidden Power Fighting or Clear Smog, or ensure that Ferroseed's hazards do not become overbearing with Hidden Power Fire, it almost always chooses to use the slot on handling opposing Foongus, because opposing Foongus are that much more difficult to build against. During these Foongus mirror matches, the main way one player is able to gain an advantage, short of stalling out Synthesis or Sludge Bomb PP, is to switch to a Foongus check or Tectonic Rage Diglett while it is using Synthesis (do note that Tectonic Rage Diglett almost never OHKOes Foongus from full health, even if it is Knocked Off).
Without Regenerator, Foongus wouldn't even be viable, as many a teambuilder who forgot to change its ability from Effect Spore can attest to. The whole point of Foongus is that it is able to outlast both its checks and the things it checks alike, while significantly threatening the opposition once it's in play with Spore. If Regenerator is banned, Foongus would not be able to do that. Foongus's statistical bulk isn't actually very good for a dedicated defensive Pokemon, and it tends to be 3HKOed by most of the things it checks; to have any hope of being able to last through the match, a Regenerator-less Foongus would have to click Synthesis constantly. If it's clicking Synthesis constantly, then it can't take advantage of Spore or its decent attacking stats (for a defensive Pokemon). And on top of that, it still wouldn't be able to outlast many opposing threats; being so reliant on Synthesis to stay healthy would cause the move's limited PP to shine through.
Mareanie
Mareanie has really been picking up in popularity recently, and for good reason; being able to completely shut down some of the metagame's biggest threats is helpful, to say the least, and if Mareanie continues to rise, then it's likely that these threats may not be ranked near the top for long. The only reason Mareanie isn't sitting alongside Mienfoo in S is the presence of Diglett. Now, claiming that a metagame without Diglett would be less fun is terrible reasoning for an anti-Diglett ban stance, and should never be used in a serious argument. However, Mareanie's existence is pretty good evidence that the reverse claim of a metagame without Diglett being more fun, or even as fun, doesn't hold very much merit, either. Mareanie is so good in matchups that don't involve Diglett that it's extremely strong to the point of approaching brokenness even with Diglett in the tier; thanks to Regenerator, Mareanie has no trouble coming in, spreading Knock Off and status, and then swapping back out throughout the match. Having fewer weaknesses means that it's even better at hard walling threats than Mienfoo and Foongus are, causing it to be more toxic to the metagame in that regard.
Mareanie wouldn't be rendered completely unviable if Regenerator was banned, as its typing is quite useful, and unlike its Water/Poison-type brethen, it has access to reliable recovery. It most certainly wouldn't be very good, either - discussions about Merciless died down rather early on into SM for fairly obvious reasons. Like Foongus, its statistical bulk isn't very good; without Regenerator, it would be far more reliant on Recover to stay healthy, leaving it with less opportunities to take advantage of its decent support movepool, and far more turns for Diglett to come in on it. If Diglett was to be banned alongside Regenerator, then Mareanie without Regenerator might become decently viable, perhaps a B Pokemon, as it would be the best choice for a Water/Poison-type for slower, semistall teams, offering reliable recovery over Tentacool's role compression and Skrelp's power.
Slowpoke
Unlike the first three Regenerator abusers, Slowpoke is comfortably not broken in the current metagame; its weaknesses to Knock Off and VoltTurn are far too detrimental in a tier where Knock Off and U-turn can almost compete with Stealth Rock as the best move in the game. However, Slowpoke's role in LC can still be construed as somewhat unhealthy. It completely neuters certain Pokemon if the opposing team has them, creating rather uninteractive gameplay by simply coming in on these Pokemon and immediately forcing them out, hoping for a Scald burn on whatever comes in on Slowpoke for there. Due to the fact that Slowpoke isn't very common, this is rarely seen as an issue, and the Pokemon that it hard walls still maintain about the same amount of viability as they would in a metagame without Slowpoke. However, getting rid of Regenerator would eliminate this issue entirely. Without Regenerator, Slowpoke's niche would likely be completely changed but not removed, as at the end of the day, its movepool and stats are actually quite good, allowing it to possibly work as a Calm Mind or Curse sweeper that can still hard wall what it needs to.
III. Regenerator's warping of the metagame
While I feel that a Regenerator ban has plenty of merit on the grounds of it being broken alone, and Mienfoo, Foongus, and Mareanie are all overwhelmingly strong due to Regenerator, arguments could be made for it being too much in terms of metagame health as well. I touched upon this in the previous section for Mienfoo and Foongus, and those two in particular are the main culprits in this regard, as they are two of the most centralizing Pokemon in the metagame alongside Diglett (with Vullaby and Pawniard ranking slightly below in my eyes). If Foongus and especially Mienfoo were banned or heavily nerfed, the metagame would almost assuredly evolve to become almost unrecognizable compared to the current one, certainly to a far greater extent than any of the past few bans that SM LC saw. Mareanie isn't currently overwhelmingly centralizing but is looking to become so at this rate, with Timburrs already beginning to frequently run Thunder Punch.
I won't go into detail on every single one of the specific metagame standards that have resulted from Mienfoo being the face of LC for so long, but I'd like to talk about a few of them just to emphasize how there are vastly more trends resulting from Mienfoo than any other Pokemon in LC. One of the more important trends that Mienfoo enforces is that Normal-types that aren't also Flying-type are rendered all but unviable; Munchlax, Lickitung, and Buneary among others have large movepools to take advantage of their fantastic stats, but their weakness to Fighting is so detrimental that their perks aren't worth it at all. This is undoubtedly primarily due to Mienfoo, as the likes of Munchlax and Lickitung would surely be able to outlast any other Fighting-type. Pawniard and Scraggy have the means to muscle through Mienfoo, and as a result, their viability hasn't dropped quite as much, but it's hard to argue against them rising by a full rank if Mienfoo is to be nerfed. On the other hand, Spritzee is prominent despite its serious drawbacks due to its reliability in checking Mienfoo. Most importantly, Regenerator Poison-types being top tier for their ability to keep up with Mienfoo - we're basically forced to check broken with broken. Mienfoo's influence extends far beyond simply making specific Pokemon better or worse, however; teams based around VoltTurn have consistently ranked among the most dominant archetypes in the metagame for years, and Mienfoo is the centerpiece of this archetype. The reason for VoltTurn being so strong is that it is exceptionally consistent and reliable, and the reason they are so consistent and reliable is because Eviolite Mienfoo is extremely difficult to take out. Without Mienfoo, VoltTurn-based teams would lose much of their safety, allowing the archetype to better fall in line with other strategies. Again, this is not an exhaustive list, as Mienfoo is far too influential for constructing such a list to be feasible.
Foongus is less influential than Mienfoo, but still easily one of the top 5 most influential Pokemon in LC, most likely top 3. Almost every coverage move for Pokemon that struggle against Foongus otherwise is geared towards getting around Foongus first and foremost, including but not limited to Ice Punch on Timburr, Ice Beam and Psychic on Staryu, and Psychic Fangs on Carvanha. Furthermore, if we were to pinpoint the single biggest reason for Water spam falling off, Foongus would be that reason, even moreso than Snivy. It and Snivy are also pretty much the sole reasons for this when you look at how much Foongus puts a stranglehold on what Grass- and Poison-types you should use on a competitive team, as it's simply so much better than its competition at what it does; the other viable Grass- and Poison-types in Snivy, Ferroseed, Mareanie, Croagunk, and Alolan Grimer have to be radically different from Foongus to be able to maintain their viability. We would likely see much more diversity in our choices for defensive Grass- and Poison-types without Foongus. Moving on to other Regenerator abusers, Mareanie is probably among the top 15 most influential Pokemon, if not higher, despite only recently picking up in usage. It doesn't dictate coverage moves to anywhere near the same extent as Foongus, but you still see a lot more Thunder Punch Timburrs and Thunderbolt or Psychic Staryus than you would in a metagame without Mareanie. Slowpoke is at least ranked higher in terms of influence than Tirtouga.
My main point is that there are a lot of metagame trends that can be traced directly to these Pokemon. The reason why there are more trends because of Regenerator users than because of the other comparably effective S rank Pokemon is precisely because of Regenerator. If you aren't prepared for a Regenerator Pokemon, you're completely shut down; a non-Regenerator Pokemon can be gradually worn down by chip damage or pressuring them with strong offensive Pokemon, even if the rest of the team is weak to it, but these simply aren't feasible solutions for dealing with Regenerator Pokemon. Being prepared for Regenerator Pokemon is far more necessary for any amount of consistent success than being prepared for your average threat.
Other than the sheer amount of metagame standards that result from the top Regenerator Pokemon, a lot of them tend to be less than ideal. Most notably, they cause Diglett to be much stronger in several ways; the most obvious one is that Mienfoo is, by a noticeable margin, the single best partner for Diglett in the metagame. A subtler, but arguably even more important cause for Diglett's strength is that Regenerator Pokemon essentially being immune to chip leads to being able to guarantee their removal becoming much more important, and Tectonic Rage Diglett is one of the few ways to do this, alongside fellow trappers in Wynaut and Trapinch and unreliable lures. Another Pokemon whose presence is often frowned upon in terms of metagame health is Abra. Abra's viability is heavily dependent on how well it deals with the most popular metagame threats, seeing how it is relatively straight-forward to trap and play around as a safety net otherwise; it just so happens that the top Regenerator Pokemon are all quite weak to Abra. With that being said, Abra's presence isn't as good of an argument to ban Regenerator, as the existence of Regenerator doesn't inherently improve the viability of Magic Guard safety nets the way it does for trappers, but it may be worth noting anyways.
IV. Suspecting policy and banning Regenerator
There may be some concern regarding whether banning Regenerator is the way to go - wouldn't banning Mienfoo, Foongus, and possibly Mareanie mostly solve the issue as well? In this case, I believe that banning Regenerator is the most elegant and preferable solution.
Firstly, note that we are
not discussing a complex ban. The discussion here is on whether to ban Regenerator and only Regenerator - enacting complex bans, such as banning Regenerator solely on Mienfoo and Foongus, could lead to a slippery slope where we come up with more and more complicated bans to eventually allow every Pokemon in the tier (for example, we could theoretically balance Scyther by disallowing Knock Off and offensive STAB moves on it), leading to an overly complicated banlist. It is also much more comparable to banning a Pokemon than to banning a move. While any of the best moves in LC - Stealth Rock, Knock Off, U-turn, Defog, Earthquake - could be framed as "broken" when compared directly to a single Pokemon, this is simply because giving up a moveslot is far less costly in the teambuilding process than giving up an entire Pokemon. On the other hand, while any given team will have room for 24 moveslots, it will only have room for 6 Pokemon and 6 abilities; you can only have one ability per Pokemon, so unlike choosing a move, choosing an ability means that you are completely excluding the potential benefits of all other available abilities. The choice of an ability is important enough to be tied directly to a Pokemon's viability in more cases than not.
Generally, we only ban non-Pokemon elements if they are legitimately what breaks the Pokemon. I have already argued that several Regenerator users are too strong, and I am confident that Regenerator is what causes them to be so; as I discussed earlier, banning Regenerator would surely cause all of its current users to become balanced. Regenerator causing multiple Pokemon to potentially be broken certainly supports this view. Furthermore, if we consider how Regenerator would affect otherwise viable Pokemon, it's likely that the vast majority of them would become overbearing to at least the extent that Mienfoo and Foongus are - just imagine Magnemite, Timburr, or even Frillish with Regenerator. The exceptions here would be Pokemon that are already heavily reliant on their abilities to be viable in the first place, such as Diglett and Snivy.
The main argument against banning Regenerator would be the collateral it causes; while Mienfoo, Foongus, and Mareanie may need to be nerfed, Slowpoke and Solosis are already well balanced. However, I do not think that Solosis meets the baseline in terms of viability to be considered here; it's already more or less completely unviable regardless of its ability, with its sole niche on Trick Room teams departing from LC with Porygon, and whether or not Regenerator is available to it won't change the fact that no competitively minded team will include it. Slowpoke is more of a cause for concern, but while it would definitely get worse without Regenerator, I think that it would still have somewhat of a niche as a setup sweeper and/or utility check thanks to its great stats and movepool, as I mentioned earlier. An argument could also be made that removing Reckless Mienfoo and Merciless Mareanie sets from the tier by banning the broken Regenerator abusers directly would cause larger collateral than removing Regenerator variants of Slowpoke and Solosis from the tier.
In conclusion, I think Regenerator should be banned.
