Resource SM OU Viability Ranking Thread

[p2]

man tang is so overrated idk why these a+ noms keep coming up because tang just really isnt as good as its being made out to be

tang is uturn bait for so many good mons in the meta like gren or koko so basically everytime they're uturning into tang, you've opened a massive hole for something like medi or maw, which either blow apart tang or something on the team because its fuckin impossible to keep them in check defensively.

it just invites far too much stuff in because av lacks the deterrence to do much that phys def has, but phys def just folds to a lot of stuff running around and its just a much less valuable team slot when it comes down to it.

if anything, pex should be a+, its sure as hell weak but the upsides of running pex are massive compared to tang (tspikes/scald/much better overall bulk and in general its a lot harder to abuse like you can abuse tang)

please stop overrating tang to hell though, it is absolutely not on the same level as say celesteela (which should probably be s regardless but ill bring that up again some other time)

 

[Mame YO]

I agree with p2's sentiment. As an example tied to my previous post - tangrowth is just begging for a mon like gyarados to come in and sub on Tang's switch. And if you aren't switching tangrowth, you're probably giving gyarados a chance at 2 dragon dances before sub breaks unless you're carrying rock slide, which isn't nearly as common as the standard set which includes earthquake instead. Then you've got a +3/+2 monster on your hands because tangrowth can't stop mons like that from doing what they want to do. Zard Y coming in on tangrowth is another good example of a mon likely to take advantage. Tangrowth is just too passive to warrant A+ imo. It's because of this passivity that allows teams to take advantage and setup or get a free pivot into it. I mean, I guess if you play it with a hit & run mentality and go for the double switch a lot... but then what happens when you guess wrong?

 

[Marrrrrrrrrr]

To be fair, Greninja and Tapu Koko can U-turn on any Pokemon and therefore create a hole for Mega Medicham, as pretty much everything that switches into Greninja or Tapu Koko is slower than it. You said it yourself, it's fucking impossible to keep them in check defensively. "It just invites far too much stuff in." And Toxapex doesn't? Toxapex is by far the more passive of the two. Scald isn't that great of a merit since Zapdos, one of its best switch-ins, doesn't care about Scald whatsoever, especially when Scald is piss weak and 70% of the time you end up doing nothing. Tangrowth has the ability to do stuff to its switch-ins, Earthquake hits Mega Charizard X, Hidden Power Fire hits Mega Scizor, Hidden Power Ice hits Zygarde and Garchomp, Rock Slide hits Volcarona, etc. Tangrowth has the same amount of survivability as Toxapex and I think Toxapex the overrated one, because it's able to consistently stay alive during a match, it doesn't do a lot else outside of just that.

Mame YO: Why would you bother keeping Tangrowth in on sub Gyarados and flat out let it get to 3+? Tangrowth has teammates. "but then what happens when you guess wrong?" A large majority of stall Pokemon have that problem, and it doesn't change the fact that Tangrowth can still cripple these Pokemon.

 

[UltraBallz]

I agree with p2's sentiment. As an example tied to my previous post - tangrowth is just begging for a mon like gyarados to come in and sub on Tang's switch. And if you aren't switching tangrowth, you're probably giving gyarados a chance at 2 dragon dances before sub breaks unless you're carrying rock slide, which isn't nearly as common as the standard set which includes earthquake instead. Then you've got a +3/+2 monster on your hands because tangrowth can't stop mons like that from doing what they want to do. Zard Y coming in on tangrowth is another good example of a mon likely to take advantage. Tangrowth is just too passive to warrant A+ imo. It's because of this passivity that allows teams to take advantage and setup or get a free pivot into it. I mean, I guess if you play it with a hit & run mentality and go for the double switch a lot... but then what happens when you guess wrong?

Ok, so one point I do want to make on this discussion is that gyara definitely doesn't sub up on tang as giga does 26 min to normal Flyinium-Gyara plus you probably aren't staying in anyways so saying tang gives gyarados a +2 or +3 isn't really true, most likely you are pivoting to something else anyways. Main point I am just trying to make is subs don't stick if tang decides to stay in.

As far as actually raising Tang though, I see both sides of the argument and don't have too much to add, just wanted to point out the Gyara calc was incorrect. Really the only thing that truly sets up reliably on Tang is Volcaraona (outside of Rock Slide) since other common set up mons lose to things like HP Ice. This thing does have over 100 ATK and special ATK so it isn't really as passive as what some people are saying in this thread. It does hate getting u-turned or volt switched on with things like Medicham and Mawile in the tier now so I definitely agree with P2 on that and that would be the main reason not to move it to A+.

Edit: Autotomize Steela also comes to mind as something that sets up on Tang

 

[robopoke]

man tang is so overrated idk why these a+ noms keep coming up because tang just really isnt as good as its being made out to be

tang is uturn bait for so many good mons in the meta like gren or koko so basically everytime they're uturning into tang, you've opened a massive hole for something like medi or maw, which either blow apart tang or something on the team because its fuckin impossible to keep them in check defensively.

it just invites far too much stuff in because av lacks the deterrence to do much that phys def has, but phys def just folds to a lot of stuff running around and its just a much less valuable team slot when it comes down to it.

if anything, pex should be a+, its sure as hell weak but the upsides of running pex are massive compared to tang (tspikes/scald/much better overall bulk and in general its a lot harder to abuse like you can abuse tang)

please stop overrating tang to hell though, it is absolutely not on the same level as say celesteela (which should probably be s regardless but ill bring that up again some other time)

Yo dude, you can always stay in with the mon and predict the U-turn. Now who is in the bad spot? If u always play obvious and go to AV Tang on the Koko, you deserve getting gangbanged by Mega Medicham and co. Making the obvious play is only advised if you do not get punished for it. If ur team gets punished by it, then it is either a missplay (making the obvious play when you cannot afford it due to matchup), teambuilding fault (your team isnt fat enough to make the obvious and safe plays) or a missprediction (well this is part of pokemon).

The good thing abt AV Tang is that you can slap it on your offensive team because otherwise, you might have to sack a mon anyways to the Koko.

Regardless, I agree that Tang should stay A because the mons in A+ are just on a different level.

Not sure how this works because it is the first time I am posting here:
Magearna from A to A+:
Magearna is a menace to offensive teams with its Trick Room set and depending on the Zmove it will destroy your team if you do not have a Chansey. Even if you have, pressuring Chansey is not really hard and Focusblast on the switch + Z Focusblast kill Chansey after some little prior damage.
Not knowing which Z move it has forces the opponent to sack another mon because the mon on the field might check Magearna at +1, but not at +0 with the correct Zmove.
Shift Gear sets are also usable. The pro and cons should be obvious by now to everyone.

Another tool I am beginning to like lately is Calm Mind Magearna even as a standalone mon (or Baton Pass)
http://replay.pokemonshowdown.com/gen7ou-561113226

While it does not have the sweeping potential unless you use Double Dance (which needs lots of offensive support to weaken the mons you can barely touch) it can heavily dent mons like Mvenu or Toxapex with boosted Flash Cannons or Tbolts. With a Shuca Bery you can even take Adamant LO Mamoswines Eq and proceed to Flash Cannon that beast.

Nasty Plot pass from Mew is also very deadly. Mews typing invites mons that Magearna comfortably can setup a Shift Gear/Trick Room on. If you use this set, make sure Mew is slow to provide a safe Pass.

 

[Night Train Lane]

Yo dude, you can always stay in with the mon and predict the U-turn. Now who is in the bad spot? If u always play obvious and go to AV Tang on the Koko, you deserve getting gangbanged by Mega Medicham and co. Making the obvious play is only advised if you do not get punished for it. If ur team gets punished by it, then it is either a missplay (making the obvious play when you cannot afford it due to matchup), teambuilding fault (your team isnt fat enough to make the obvious and safe plays) or a missprediction (well this is part of pokemon).

the problem with this scenario is that the Koko user, under most circumstance, has little reason to not just thunderbolt or hp ice. (same thing with Ash-Greninja because you are basically forced into AV Tang in order to not let it evolve) Even if you go to your AV Tang it has very limited options of doing anything in return, so you can just U-Turn out to anything that can take advantage. As p2 said Medi, Mawile, Scizor Ferrothorn etc. Whereas a pokemon like THAPEX can actively get momentum with scald burns and toxic spikes. (Not off of Koko obviously, but pokemon that it beats.)

I generally don't agree with Mag to A+ but I don't have TOO much experience with Trick Room exclusively, other than sweeping and being swept by it. The AV and Shift Gear sets aren't good enough for a raise imo

 

[robopoke]

the problem with this scenario is that the Koko user, under most circumstance, has little reason to not just thunderbolt or hp ice. (same thing with Ash-Greninja because you are basically forced into AV Tang in order to not let it evolve) Even if you go to your AV Tang it has very limited options of doing anything in return, so you can just U-Turn out to anything that can take advantage. As p2 said Medi, Mawile, Scizor Ferrothorn etc. Whereas a pokemon like THAPEX can actively get momentum with scald burns and toxic spikes. (Not off of Koko obviously, but pokemon that it beats.)

If your breaker like Mega Medi is at half, you are pressured to Uturn immediatly with Koko. If you Tbolt+Uturn the AV Tang, Mega Medi dies to Tangrowths attack. It is a predictiongame in favour of the Uturner obviously. But the plethora of moves Tang can run to threaten its switchins are insane. It is not that passive.
Yes, Toxapex can TSpike/Scald burn and Tang can do 50% to your switch in. Still think it does not deserve A+ because it is predictionreliant and is not as easy to use as the mons in A+.

 

[Mr.Goxel]

The theory mon shit here is kind of annoying. Seriously no valuable points are being made and people are just theory moning up the ass.

Anyway Toxapex for a+ I'm not really for. It's just way to damn passive. Like marrrrrrrrrr said, it switches in and could in theory get spikes up, but what the hell else is this thing gonna do? It's scald is weak af and most things switching into this thing don't care about the burn. The meta is filled with steels right now so it has trouble spreading poison. It's good don't get me wrong I hate when people nom shit to like A- and say this mon is so underwhelming because toxapex really isn't it does put in some work but not enough to make it as good as other A+ mons

 

[Vert]

no one is keeping tapu fini in in front of a tapu koko since more than half of them have volt switch. you are basically forced to take a huge hit (which is dumb) or invite medicham in for free. yes, i know it is a lose-lose situation. tangrowth shouldn't be higher because of how the metagame is introducing more threats that are unfriendly towards it.

toxapex is easy to fit on builds and is not prediction reliant. i wasn't aware one of the most common 'mons in the tier for balance, stall, and bulky offense was hard to fit on builds. i also wasn't aware alternating between scald, recover, and toxic(spikes) was so prediction reliant either! this point is also flawed. toxapex is a great pokemon that is a contender for a+

i would also watch who you are talking to mr. goxel when it comes to theorymon'ing. p2 and robopoke did not theorymon in the slightest and you yourself constantly theorymon in this thread. the irony -_-

 

[volx757]

Ok, so one point I do want to make on this discussion is that gyara definitely doesn't sub up on tang as giga does 26 min to normal Flyinium-Gyara plus you probably aren't staying in anyways so saying tang gives gyarados a +2 or +3 isn't really true, most likely you are pivoting to something else anyways. Main point I am just trying to make is subs don't stick if tang decides to stay in.

I agree you shouldn't be subbing on tang, but it's cause you don't need to. You just outright beat it. You can even set up a DD first for free. You switch into tang's knock, HP, and rock slide does like 35. So most likely you're using it as bait and going for a sweep.
252 Atk Gyarados Bounce vs. 252 HP / 4 Def Tangrowth: 420-494 (103.9 - 122.2%) -- guaranteed OHKO (that's SSSS)
I brought up a gyara rise in the last VR, and I think I could still get behind one. It just sets up on soo many things, and if the opps scarfer is gone, you just need 1 DD and its gg.
It grabs free DDs on passive shit like tang, fini and pex (only go for 1 so you kill them before they haze you), gets DDs on defensive landot, it grabs DDs on super aggressive shit like ninja. The main points against it are increased usage of zapdos and washtom, two of it's hardest checks.
But yeah it's a great wincon, certainly better than Mega pins imo (A-).

And the set for the rise is dd/waterfall/bounce/eq (not taunt). EQ is absolutely necessary for guaranteed OHKO on koko, better than 50% chance to OHKO magearna, breaking toxapex, etc.

 

[robopoke]

I wouldnt call Fini passive shit when it Natures Madness on your DD and Moonblast on your SSSS since Fini eats one. Now your Gyarados is at 20% health and is easy to revengekill. It can definitely setup easily if you have Rocks up and DD on the Defog. Otherwise it is not a super reliable setup target.
Trying to setup on Toxapex is also risky. If you DD once and Eq twice, you risk getting Scaldburned with probability of 1-0.7²=51%. 51% chance to lose the setupgame and you call it passive? If it is physdef with Toxic, it can Toxic on your DD, Haze on your +1 Eq and still be healthy enough to take +0 Eq unless max rolls thus being able to recoverstall and potentially win the 1vs1.

Being able to setup on defensive Landot is one of the many reasons it is higher ranked than Salamence and is not an argument for a raise.
Unless new Zmoves are used on Gyarados that will favour current metagametrends (not sure if there are other good ones, I will test later), I do not see it being raised.

 

[LORD HELIX 65]

I would like to nominate Dragonite to B from B-. I have swept many times with dragonite with a dragon dance set holding an electrium Z. After a single dragon dance, it can do serious damage to many pokemon in OU, like skarmory with thunder punch, Toxapex with earthquake, Nihilego with earthquake, and checks other things in OU, like gengar with earthquake, and salamece with dragon claw. If you decide to run a Dragon dance/Aerial ace/Thunderpunch/Dragon claw set instead of a Dragon dance/Earthquake/Thunderpunch/dragon claw set, you can check other things more reliably like Tangrowth, Volcarona, Buzzwole, and Tapu Bulu, which are all pokemon high up on the viability rankings. Getting set up isn't very hard at all if you have it's hidden ability multiscale, which halves damage from any attack, however, it can easily be broken with things like stealth rock and weather like hail and sandstorm i think, so i use it early game and usually get to +2 or 1 without too much trouble, and it always can KO at least 1 or 2 pokemon without much trouble, and it can sweep if you play it right, i have swept with it quite often. Unfortunately, Dragonite struggles with common pokemon like Lando-T, and may struggle with other popular pokemon like protean greninja and Tapu Lele, So i feel it should be raised, but only to B rank.

 

[Nuked]

I don't think Tangrowth should rise to A+. Tangrowth is a solid A mon and deserves its spot there because it's great at what it does, but it's not at the level of the other A+ mons. P2 made solid points in the fact that most of the mons it checks (Koko, Lando, etc) can just U-turn on the switch since it's obvious, go into Medicham / Mawile, and kill something. This really isn't uncommon in matchups where teams utilize Medicham + Koko and is something that actually happens a fair bit. Tangrowth can really be taken advantage of by its passive nature; (110 special attack is less when you're using weak coverage moves like HP Ice, weak STAB moves like giga drain, etc) it more or less just gives setup to some massive threats like Volcarona and Gyarados because it really can't do much damage back, unless you're running a specific coverage move for it, in which case you'd be dropping what is usually a more valuable moveslot. Like I said it's a solid A mon and is definitely a good Pokemon that I use a lot too but it isn't on the level of other huge metagame threats like Medicham, Lele, Celesteela, etc

 

[Fire Fist Ace]

Could someone please explain to me why Mega Garchomp is even ranked on the VR? It has an ASTOUNDING 0.6% use as of the last usage stats update, and I fail to see any real reason to use this on any team when there are so many better Mega options available, and some aren't even OU by use.

I'll go further with my explanations if anyone agrees with this sentiment.

EDIT: MEGA Garchomp. I meant it. And I know it. Just forgot to notice.

 

[Randompizza]

Fire Fist Ace last time I checked megachomp is ou by technicality. Meaning since it's normal form is in ou it has to be in ou too since you can't use the mega without the regular. And correct me if I'm wrong since I'm a little rusty on vr policies, but mons that are in a tier have to be put on the vr since they are in that tier. Which makes since.

 

[Gary]

Nah they don't have to. Mega Chomp has a niche of being an extremely powerful breaker that's also super fat, but its definitely falling off quite a bit in viability with Mawile and Medicham in the tier giving it competition. It's still decent though purely by typing and combo of raw power and bulk.

 

[Toshiro46]

Might be a little controversial, since this mon was suspected and all, but:

Dugtrio A -> A-

Despite being the best trapper this gen, it suffers from a number of glaring flaws that hold it back. It has paper thin defenses, low base attack, and a speed tier that notably leaves it outsped by Greninja. Furthermore, it can't run all the moves it needs to be a truly effective trapper, as it wants earthquake, sucker punch, memento, reversal, stone edge, rock slide, screech, and even SR, toxic, and aerial ace.

Of course, all this was true when it made its way to the A Rank, so what metagame trends no longer favor it?

Spikes. Dugtrio fucking hates Spikes, because when Spikes are up its focus sash is useless. With the complete lack of reliable hazard control in this meta, using dugtrio is getting more and more unreliable as you can't guarantee its sash being up. What makes matters worse is that Greninja and Ferrothorn, the big spikes users, both don't really care about it. Gren carries Ice Beam, outspeeds dug, and isn't OHKOed by EQ while Ferro is way too bulky to care about Dugtrio. Without reliable hazard control, Dug's trapping suffers greatly. It can't trap any of the frail things that outspeed it anymore, it can't trap any of the bulky things that can take a hit from it (Megagross), and it can't trap anything with decently strong priority.

Another thing that I'd like to add is that people are much more prepared for Dug now, running shed on the mons that exist on a team to combat stall, being more wary of double switches, etc. It's not nearly as metagame warping as it once was, which is reflected by its absence on non-stall (and non-CharY ig) teams of late.

Because Spikes are what they are in the meta as of right now, Dug's effectiveness outside of stall (where hazard control is so much more effective than anywhere else) is diminished greatly. Due to that, I think it should drop to A-.

 

[piikachuu]

i'm a little confused. you mention spikes as a problem for dugtrio because they break its sash, and that spikes are more common now and dugtrio doesnt beat common spikers, but rocks are on literally every team and do the same thing. its not like duggy beats the most common rocker, landot, either.

(no mention on the rest of the nom, though, just wanted to point out the rather strange argument)

 

[Toshiro46]

i'm a little confused. you mention spikes as a problem for dugtrio because they break its sash, and that spikes are more common now and dugtrio doesnt beat common spikers, but rocks are on literally every team and do the same thing. its not like duggy beats the most common rocker, landot, either.

(no mention on the rest of the nom, though, just wanted to point out the rather strange argument)

The point is that hazards are more prominent and easy to get up than ever, and hazard removal is in an abysmal state. This does not bode well for Dug.

 

[robopoke]

Might be a little controversial, since this mon was suspected and all, but:

Dugtrio A -> A-

Despite being the best trapper this gen, it suffers from a number of glaring flaws that hold it back. It has paper thin defenses, low base attack, and a speed tier that notably leaves it outsped by Greninja. Furthermore, it can't run all the moves it needs to be a truly effective trapper, as it wants earthquake, sucker punch, memento, reversal, stone edge, rock slide, screech, and even SR, toxic, and aerial ace.

Of course, all this was true when it made its way to the A Rank, so what metagame trends no longer favor it?

Spikes. Dugtrio fucking hates Spikes, because when Spikes are up its focus sash is useless. With the complete lack of reliable hazard control in this meta, using dugtrio is getting more and more unreliable as you can't guarantee its sash being up. What makes matters worse is that Greninja and Ferrothorn, the big spikes users, both don't really care about it. Gren carries Ice Beam, outspeeds dug, and isn't OHKOed by EQ while Ferro is way too bulky to care about Dugtrio. Without reliable hazard control, Dug's trapping suffers greatly. It can't trap any of the frail things that outspeed it anymore, it can't trap any of the bulky things that can take a hit from it (Megagross), and it can't trap anything with decently strong priority.

Another thing that I'd like to add is that people are much more prepared for Dug now, running shed on the mons that exist on a team to combat stall, being more wary of double switches, etc. It's not nearly as metagame warping as it once was, which is reflected by its absence on non-stall (and non-CharY ig) teams of late.

Because Spikes are what they are in the meta as of right now, Dug's effectiveness outside of stall (where hazard control is so much more effective than anywhere else) is diminished greatly. Due to that, I think it should drop to A-.

On offense I wouldnt run Focus Sash Dugtrio but Items like Groundium Z because trying to get rid for hazards just for Dugtrio loses so much momentum. Id argue that on any playstyle other than Stall, Groundium Z is the better Item because
1) You are not pressured to get rid of Hazards
2) Dugtrios Z-Eq is very powerful, being able to oneshot huge threats like Mega Medicham and is more reliable against Toxapex.

The good thing abt Focus Sash is that you can switch into a weakened Lele (example), eat the sash and kill it with Eq or reliably Eq against Mega Mawle who tries to Sucker you. That is very valuable to teams that can afford to run excessive hazard control. But for stall, nothing has really changed to be forced to run other moves than Focus Sash.

To me Duggi is a mon who shines on stall and is mediocre on every other playstyle. It is indeed questionable to see it in A with mons like Koko, Garchomp and Volcarona. I guess you can argue that it is almost 100% necesarry on one playstyle that makes it deserving A? Not sure.

 

[Gary]

Pokemon that are OU simply by usage do not guarantee them a spot in the rankings

I've added this to the rules in the OP just so everyone is now 100% clear that Pokemon don't have to be ranked even if they are OU by usage. Personally I've always thought it was a dumb idea to rank Pokemon for the sake of it, so now I'm going to make it official. Thanks.

 

[Toshiro46]

On offense I wouldnt run Focus Sash Dugtrio but Items like Groundium Z because trying to get rid for hazards just for Dugtrio loses so much momentum. Id argue that on any playstyle other than Stall, Groundium Z is the better Item.

To me Duggi is a mon who shines on stall and is mediocre on every other playstyle. It is indeed questionable to see it in A with mons like Koko, Garchomp and Volcarona. I guess you can argue that it is almost 100% necesarry on one playstyle that makes it deserving A? Not sure.

And the issue is of course that without sash, even if it's running another item, it's much less consistent, which is why it now is less effective on every play style besides stall.

I don't think being necessary on stall and mediocre everywhere else should put it in A. Mega Sableye and Chansey are the same way and exist in A-/B+, and both (especially Sableye) are more vital to stall than dug is. All other mons in A fit on more than one playstyle effectively. Putting Dug in A- with its fellow trapper and fellow stall staple makes sense.

Edit Muscle K:

The point to my nom is that after Phero's ban, hazard removal is shit and spikes are everywhere. When Starmie, a mon residing in C for nearly all of SMOU's lifespan, is considered the best hazard removal option, you know something's up. If you require Starmie to use Dug effectively on offense, then you're limiting it to the kind of team support that I'd expect from mons in A-, like CharY or Mega Sableye.

First, you say that scarf dug is incredibly underwhelming (which I agree with, especially since Phero's ban). Then, you say that it's really good right now. Pick one. Both choice sets forgo the utility of Dug's other moves, like screech, Memento, and sucker punch, which is pretty taxing to Dug's trapping, and they both mean that dug can't switch into mons it'd like to with focus sash. The Band set, unlike what you've said, has lots of drawbacks. Most I've gone over and boil down to "it's way too easy to kill and much more unreliable without sash". In addition, many of the mons you mentioned (CharX, Volcarona, Magearna) are often going to be sweeping if you want to revenge them, and if they're sweeping they're gonna be speed boosted, which means Band can't do shit to them anyway before being KOed. Its only real draw is KOing Megagross, but good luck switching into it.

As for your last paragraph, arguing that fucking Lando-T being used is evidence of Dugtrio's influence on team building is ridiculous. The same goes for Skarmory (only used on stall anyway), Tangrowth, RotomW, and Bulu (which isn't even that common anyway and even less so due to a fear of dug). RotomW is used because it's an effective pivot, dealing with Dug is just a plus. The same goes for Tang except it's also a blanket check to the meta. Lando is fucking Lando and present on 50% of teams regardless of Dug. Stallbreaker Lele is a stallbreaker. Of fucking course it's going to run shed shell, its entire purpose is defeating stall. Heatran is much the same way, but shed shell is a pretty trash set on it anyway. None of what you say in this paragraph is evidence of Dug's influence on the meta and frankly speaking it kinda sounds like you're just making stuff up as you go along. The scarf dugtrio comments come to mind.

 

[Night Train Lane]

You don't need a sash on Dugtrio is the thing you're not getting. As robopoke said Z-Quake or scarf is a much better options outside of stall builds that give much more utility than sash and people are starting to use Sub Zmove on stall to get around Mawile and revenge a wider range of breakers.

It should still stay A, being able to trap or revenge 70% of the tier, and is a wonderful support option on many team builds.

 

[StraightEdgeNexus]

B- -> B+
Mega shrimp is an underrated threat as a DD sweeper. A great attack stat along with ever useful mold breaker and a decent speed tier makes this an amazing sweeper as well as a stallbreaker with taunt (2hkos everything at +1 except for toxapex). It also resists most priority moves and there are almost no Mach punch users in the current meta. It can 1v1 most scarfers if I'm not wrong.
Sure it has flaws but B- is too harsh imo.
To finish this off, Imma drop this low ladder replay which isn't an achievement tbf, but there wasn't much one could do but get swept.

https://replay.pokemonshowdown.com/gen7ou-564927706

 

[robopoke]

You are suggesting Mega Gyara to B+, where regular Gyarados resides. Mega Gyara has trouble getting past Tang, Fini, Ferrothorn which are much more common than mons Z-Gyara loses to but Mega can win against like Rotom-W. Comparing Rotom-W usage with Tang, Fini Ferrothorn should already give you the answer, which of the two Gyarasets are more viable right now.
Also to beat stall, you do not need the Mega Stone but Taunt to setup on Skarmory. Mega can afford to not Taunt against Clef which gives it some breathing room but in the end it is not a huge difference.
In fact, being forced to Mega at some time during Dragon Dancing gives Duggi the potential to revengekill you with Reversal.