Let me preface this post by saying that the intentions of this post are good-natured, and it's meant to be respectful. Everyone is entitled to an opinion. I probably was a little too brief last time when I lightly touched on my stance w/ entei while responding to a question about shaymin. Accordingly, here's an in-depth analysis of my thoughts on Entei in the metagame and, to a more crucial point, why Entei deserves to be re-suspected.
Entei & How it Affects the Meta: An Overview
Before going into the specifics of how Entei sizes up to the rest of the tier, it's probably best to shortly cover what it brought to the meta that was new. For a very obvious starter, Sacred Fire brought to the table a challenge the tiers typical offensive fire resists (Tyrantrum, Aerodactyl, Flygon, and others) had great difficulty with. Extreme Speed banded from a 115 base attack mon is pretty threatening to offensive would-be checks that aren't very bulky (we have a lot of them in the tier) but outspeed Entei. Stone Edge and Stomping Tantrum are good neutral coverage moves that can ohko/2hko some of the decent typical fire resists. Flare Blitz hits ridiculously hard from cb entei, and picks up quite a few ohkos that Sacred Fire leaves to a roll or otherwise can't. Just because I don't think I'll be covering this specific point later, mons under this category include Pangoro, Nidoqueen, Meloetta, Drapion (almost guaranteed), Machamp, Necrozma after rocks, and others. This isn't the only relevance Flare Blitz carries, as often times the bonus power it offers can be incredibly crucial in landing KOs midgame/lategame. It's also one of the only mons in the tier that can successfully utilize drastically different movesets. CM Entei and Vintei both have merit, though mostly just CM Entei imo. Some prime Entei counters (think bulky waters) become fodder if you happen to be vsing the uncommon CM Entei. That's basically what it does in the tier, so now I'd like to get into what beats Entei, what doesn't beat Entei, and everything between.
Good Entei Counters
These three bulky waters to me are easily the best physical Entei counters in the tier. Milotic and Slowbro eat anything Entei would care to throw their way and happily scald away, among other moves. Pyukumuku is in a similar boat, though obviously can only retaliate with toxic/block/soak (or recover). The first one of these three I'd like to address is Slowbro. Slowbro, to me, doesn't have a large niche outside of being an inferior Milotic. I personally don't find it incredibly viable since it struggles significantly more vs the harder hitting special attackers of the tier, while Milotic can reasonably cover most mons specializing in physical or special attacks. That being said, Slowbro is still a very viable Entei counter, and arguably better than Milotic in some ways. I still don't think it's very easy to justify throwing it on a team vs just using milotic, though in a vacuum it handles physical Entei incredibly well. Branching from this, Milotic is probably the best Entei counter in the tier. It handles physical Entei as well as Vintei, so long as you're using refresh Milotic in regards to Vintei. Even special Entei isn't a guaranteed loss for Milotic, due to its incredible natural bulk+haze being such deterrents. Lastly, Pyukumuku is probably the weakest Entei counter of these three. It handles the damage just fine, though can't do much in retaliation to generally harm Entei teams imo. To elaborate, Entei is usually paired with mons to obviously patch up what it can't cover. While Milo and Slowbro can attack when Entei switches out, Pyukumuku is pretty much at the mercy of any likely counter. It's predictable, and easy to react to. If you have general answers, you don't have to worry about a scald burn, or a psychic, or even a toxic. It just doesn't have the power to punish Entei and by extension Entei teammates when countering imo. The issue of Entei team composition also plagues Milotic to an extent, as it's very easy to pair Entei with one of the tiers many Milotic counters. Offensive grasses, other Milotics, Dry Skin users, Kingdra, Noivern, and many others are viable Entei partners that have no issues with Milotic, depending on the set being used by Milo.
Rest Snorlax, conveniently paired with thick fat, acts as a pretty convincing Entei counter. Thanks to its incredible bulk and 50% fire resist, Standard CurseLax avoids any 2hko from full hp. That being said, Stone Edge does 38-45% with Flare Blitz not far behind at 34-41%, so it can tricky if you're trying to counter Entei from nonfull-hp. Being the mon it is, people happily throw Snorlax at damage as a sponge, and it isn't uncommon for Lax to be lingering around 60-70%. It's certainly not enough to counter Entei, though it can still happily check Entei. However, realizing this and catching Lax using rest isn't difficult, and you can use this for easy momentum in whatever way works. This is all hypothetical and stuff, as Lax is still one of the tiers best and only Entei counters. As a last note, Recycle Lax can work vs entei relatively ok, as long as you're facade. Taking an average of 70% vs Flare Blitz is pretty scary though, and doesn't exactly allow for an easy counter even from full.
This is about all there is for viable Entei counters, and they for sure have their flaws. Most notably, they're all relatively passive pokemon. In this relatively offensive meta we're currently in (please stay away mantine) being passive can and often is exploited.
Not Good Entei Counters
We'll start with probably the most commonly named Entei counter that simply doesn't live up to expectations in this respect. No-HP stoise doesn't handle Entei at all, as Stone Edge is literally a 75% chance to 2HKO. Flare Blitz does 85-99 in 2 hits, and even Sacred Fire does 70-82 in two hits, risking burn as well. HP-invested stoise handles Entei a little better, depending on the investment. Using the very generous amount of HP the calc set provides, Entei has a very tiny chance to 2HKO w/ Stone Edge. All 3 of Enteis other moves 3HKO this stoise that's already invested to a generous degree. Essentially, stoise can counter espeed/stab locked entei once, and then can only effectively exist vs Entei as a check. This is of course ignoring hazards, even though stoise likely switches into hazards anyway as it's the sole remover on the team more often than not. It just isn't reliable in a tier where wishpassing clerics are fairly ineffective.
These two are considered decent Entei resists, though in reality are in a worse boat than stoise. Ampharos is essentially 2hkoed by Stone Edge, while suffering a chance of 2HKO vs Flare Blitz. This is of course if Entei isn't already running stomping tantrum, which does a devastating 74-87 to amphy. In return, Amphy has no way to OHKO Entei, while stoise generally does. Dragalge fairs even worse as a defensive answer, as an offensive variant is easily 2hkoed by Flare Blitz, while suffering a potential 2HKO vs either Epseed or Sacred Fire (accounting for burn). Tantrum doesn't OHKO, though it does most likely KO after drag takes a round of rocks. The standard "defensive" Dragalge spread doesn't help, since it just adds negligible hp and spdef. Physically defensive Dragalge just isn't viable to me, it accomplishes nothing of significance outside of countering Entei while weakening yourself vs a host of threats that make bulky drag (spdef) barely viable to begin w/.
I'm lumping the two bulky grounds together since they're in a relatively similar realm here, though Rhyp handles Entei better. We'll start with Gligar though, who is one of the premier defensive mons in the tier and a hallmark for being a physical attacker repellent. Max Defense Gligar eats any moves with relative comfort. Flare Blitz maxes out at 80% after two hits, so it's a pretty decent counter if you aren't already weak. That being said, Sacred Fire is the real killer for Gligar, as a burn can be very bothersome. Outside of burned Gligar not even 3hkoing Entei with Earthquake, a burned Gligar loses a tremendous amount of presence in any given game. While it isn't as useless as other burned switchins that offer only offense viability (Flygon, Tyrantrum, others), it gets relegated to the role of solely passive support. An immediate reaction is that Gligar is just fine as non-damaging support, though I'd argue it makes games vs offensively-weak grounds pretty annoying, like Toxicroak/Barbaracle/Dragalge/Drapion and even Lycanroc, among others. It can still function as a pokemon, though it becomes a passive easy-to-abuse sitting duck. Rhyperior fairs a little better, since it takes almost nothing from any of attack Entei can throw out. That being said, burn is very annoying to a mon that can pretty much only get rocks up post-burn. It falls into the group of mons Entei uniquely can render near-useless despite offering negligible damage to them. Mind you, special Entei completely devastates Rhyperior, and it isn't the easiest thing to spot on teams unless it reveals a move.
Geez, Does This Monster Have Any Flaws?
The main valid point in my mind as to why someone would find Entei fair is that a plethora of offensive checks exist within our meta. Scarf Tyrantrum, Mega-Stoise, Noivern, Zydoge, and Aero are probably the best offensive checks in the meta. There are other relatively good offensive checks, though I don't exactly think that they're ideal for different reasons depending on the mon (espeed ravaging them while they don't OHKO is a main one for most of them though). The main gripe any Entei supporter could have is that it gets outsped by a portion of the RU meta. Despite this, many of the best Entei answers, like the bulky waters listed above, are handled by Enteis teammates. For example, Milotic goes together very well with Entei. Milotic handles pretty much every mon listed above, with Zydoge Noivern and Tyrantrum giving it the most issue, though Noivern less so if you're packing ice beam. Tyrantrum doesn't really count since that mon is utterly ridiculously to switch into, as I've been saying for awhile now.
In contrast to what threatens Entei from a check perspective, what does Entei threaten within the meta? For starters, the always present steel types. Steels don't fear any mon in the tier more than Entei arguably. Grasses also are threatened by Entei, though less so since some of our offensive grasses like Roserade or Virizion can at least notch off 50-60% before they die. Shaymin can hurt the fire dog with earth power, though I'd argue quite a few Shaymins aren't running ep anymore, as psychic and air slash have become more popular along w/ synthesis. Another group of mons that struggle vs Entei is literally almost any slower offensive mon in the tier that hasn't been mentioned and isn't Kingdra. No, really. Gardevoir, Bewear, Nidoqueen, Pangoro, Rotom-C, Toxicroak, Honchkrow, Linoone, Venusaur, Medicham, Machamp, Hoopa, and any other grass type dies to Flare Blitz. Most of these die to Sacred Fire. Even Emboar is 2hkoed by Flare Blitz. Ninetales (97%-115%) literally dies to Flare Blitz. The list goes on, but I'm sure you understand where I'm coming from by now.
This just about does it for my explanation as to how I feel about Entei relative to the current meta, so now I'll explore an even more appropriate reason for Entei to be suspected.
The Freedom, the Aftermath, and the Future
For those who are unaware, Entei was freed under very uncommon circumstances. When Entei dropped to RU alongside Mienshao and Mega-Houndoom, the council decided to ban all three of them. The exception here was that Entei was to be publicly suspected shortly after, and for fair reason. The other two were very obviously broken, while physical firedoge had sound reasoning on both sides. The suspect took off, and subsequently ended later in the month. Upon the votes beginning, I had expected it to be pretty close. People like 49 and Dodmen had made posts elaborating on the rationale behind freeing Entei, in contrast to posts made by others questioning the real benefit of Entei existing in RU. When the dust was settled, Entei was freed by one vote. It was a rare occurrence given the history of RU suspects, where landslide votes aren't uncommon. Some handled the news more professionally than others, but for better or worse Entei was now a part of RU. It's been a decent chunk of time since then, and many players of varying skill levels either still feel or newly feel it's not a healthy pokemon. It's a pretty unique situation, given I can't recall a time in recent history where an RU suspect result was so highly contested. This didn't happen with Heracross or Zoroark, with Reuniculus or Sharpedo. There's been more than enough time for the meta to adjust, but folks still feel strongly about Entei exiting the tier. Personally, I think this is the perfect time for a resuspecting of Entei. Slam is right around the corner, and for many it'd be ideal to at least have the chance of banning Entei before that is underway for long. If the community again votes to keep Entei free, then that's ok. Democracy will again have did its thing. But regardless of the result, the opportunity for a resuspect seems the most viable course, and I personally hope the TLs consider this in the very near future.
Thanks for the time if you made it this far, this is probably my longest post if not for one of my VR posts.