Hey, I don't think you've actually played with half of the things you're mentioning in this post so allow me to clarify why I feel like your reasoning is flawed.
I, for one, don't believe we should ban Shell Smash
Imo, nothing in Pokemon is so unbelievably broken that it's impossible to deal with, and Shell Smash is no exception.
This is the first thing which I disagree with, but it's a difference in our fundamentals. If you feel like nothing is broken in this game, there's not really anything I can do to convince you otherwise since your philosophy is different from mine (and Smogon's), but I'll address the remainder of your points anyway.
Let's say if the opponent has Set up 2 Shell Smashes and is strong enough to OHKO pretty much anything in the game. This could include sweepers like Darmanitan or legendaries. There's tons of ways to go against it, since Shell Smash lowers defence, and sweepers tend to be frail, they'll usually set up Shell Smash and then get knocked down to 1HP due to Focus Sash. The sweeper can then be dispatched through any priority move in the game. Shadow Sneak, Sucker Punch, First Impression, take your pick.
I agree that this is a consequence of Shell Smash - but not for the reasons you're mentioning. For starters, this is an incredibly specific scenario. Shell Smash users can also be quite bulky and they're able to resist priority moves. Solgaleo has proven to be a premier Shell Smash user in the tier, and it resists priority. When analyzing an element in a suspect test, we look to see how it performs during its best applications. This entails analyzing why priority doesn't work. Now, I still think Shell Smash can be managed - It's just that you need a separate check for Solgaleo, and other Smashers for which your priority doesn't work. Personally I feel like that's fine.
I also feel like it's important to tell you that none of the priority you listed is actually good. The priority in this tier is really only Kyurem-B and Kyurem-W.
Due to Prankster being a favourite (from what I've seen) ability in the meta, you can run Haze on a Prankster Pokemon to negate the Shell Smash. I've seen this in OU as I've seen a few Toxapex run the move to fairly decent success. Hazing out the boosts from Shell Smash give the opponent 2 options, attack or set up another Shell Smash. If I Shell Smash again, they'll have an opportunity to set up, or attack, which can put me into a bad situation. Prankster Pokemon can also take advantage of Taunt to prevent Shell Smash entirely, since most Shell Smash users tend to lead with the move from my experience. Another favourable ability to counter Shell Smash is Unaware. Possessing a bulky Pokemon with another (In my case, A Rotom-W) then you'll take less damage, which can give you time to set up, wall it out with Toxic, etc.
I actually agree with your point on Prankster Haze. However, Prankster Taunt is incredibly costly to run - Most Prankster Pokemon run the bread and butter set of Recovery, Haze/Destiny Bond, and a trapping/pivoting move. This leaves 1 moveslot to run what you can - Be that whatever you didn't select from Haze/Destiny Bond, be that Encore, be that Spectral Thief, be that Court Change... The possibilities are endless. Taunt is the least of their priorities because not only does it not always work for what you want it to (Smashers) but Taunting Magic Bounce Pokemon can be incredibly unfortunate due to taking away your method of recovery. Unaware doesn't always work, either. For starters, a lot of the moves that Shell Smashers use are already powerful in their own right. The defensive walls in this tier tend to rely on their ability to counter already unboosted variants of these Pokemon, because the offensive power level of the tier is that much higher than the defensive bulk level. That's one of the reasons why Unaware doesn't really work. The other reason is with moves like Power Trip and Sunsteel Strike in the tier, Unaware doesn't really make much of a difference. Prankster does most of the things Unaware does, but it does them better while being better utility.
Looking at the specifics, It's usually sweepers who run Shell Smash. Then there's the potential for those buffs to be stolen through Spectral Thief or Imposter+Choice Scarf, etc. Unaware is a useful ability to have in this situation and is one I've seen on Pokemon like Eternatus to great success. Since It's BH, Pokemon will usually run quite varied movests to cover potentially difficult matchups. Bulky Pokemon with few weaknesses like Galarian Corsola or Rotom Wash with this ability can easily counter Shell Smash and can wall them out with moves like Protect, Toxic, Recover and Will-O-Wisp.
I'm gonna be honest - I feel like people aren't using Imposter enough. I feel as if it's pretty good, personally, but others disagree and that's their viewpoint. I can't contest yours here, though, because I agree with that part. I've already went over why I feel like Unaware isn't fantastic, so I'll leave that part. However, Galarian Corsola (while being outclassed by Dusclops) and Rotom-W also just don't have the bulk or typing to tank a lot of the Pokemon in this metagame. The counterplay you listed is also incredibly passive, which is very easy to take advantage of and doesn't really work even vs Shell Smash.
Fast and hard hitting Revenge killers with Focus Sash also work wonders against Shell Smash. Since Shell Smash users commonly run Focus Sash (some like to run Mental Herb but that leaves them susceptible to OHKOs) That means there's defences will be lowered, which leads them wide open for kill potential. An example of this is Unburden or Weak Armor which can double your speed on the second turn if you don't kill them initially. You'd preferably want your Revenge killer to be trial like Weavile or Barraskewda so your can more easily activate Undurden. Also, since Shell Smash lowers defence and raises speed, if you were to use Trick Room, they'd pretty much be sitting ducks for pretty much anyone since you're now going to be slower than the Shell Smash Pokemon. Granted, it takes a turn to set up Trick Room, but it also takes a turn to set up Shell Smash, so yeah.
Let me explain to you why none of what you say here is correct. For starters, Focus Sash is fine, but using it means you're not using another, more valuable item. This isn't exactly unheard of nor is it necessarily bad, but there is that opportunity cost to keep in mind. On top of that opportunity cost, you either need to have Stealth Rock off the field or you need to have Magic Guard. On top of this, you need to be at full health, meaning you can't have taken damage beforehand. The only Pokemon that really fits this criteria is Galarian DarmZ, which is a fine Magic Guard Sash user, but doesn't fit on every team with this set. Weak Armor is bad - It makes you weaker, it's in the name, don't ever actually run this. Unburden isn't that great either. Trick Room also only lasts for a few turns, while Shell Smash lasts as long as you don't die or switch out.
Now that I've covered why the stuff you listed doesn't actually work, lemme tell you how you should be handling Smashers. If you use a normal wallbreaker without priority, you have to take a hit because Shell Smash Pokemon are generally faster, which doesn't always work - But you listed Scarf Imposter, Prankster Haze and Priority, all of which can work. Use those, don't use the stuff in this paragraph.
You can also run other moves like Priority Skill Swap into Truant+Protect so that you can chip away at the attacker. You can also run Skill Swap Contrary so that they lose Attack and Speed instead of gaining it. You don't lose the swapped ability upon switching, so once you Skill Swap an opponent. They'll be practically useless for the rest of the fight.
Contrary is banned and your last sentence is just incorrect, that's not how it works. Like, mechanically. It just isn't how it works. At all.
Finally, Let's talk Dynamax. Dynamax in relation to Shell Smash can be a blessing and a curse. On one hand, Dynamax makes their moves stronger, making it tougher to survive. In this instance, using Protect to last out the 3 turns or Burning/taunting/ neutralising the attacker in any of the ways discussed above can be rather effective against a Dynamaxed opponent. On the other hand, if you Dynamax, your take half damage from everything. making it easier to outlast and KO the opposing Pokemon whilst setting up yourself by gaining or lowering stats. Using Max Guard plus another move that buffs your defences or lowers your attack can be a great strategy to take care of Shell Smash.
got nothing to say here except fuck dynamax
In conclusion, as with most moves, abilities and strategies in Pokemon, Shell Smash can be adapted to and countered to without much effort. There's a lot of things that can deal with the move. In my opinion, It's no more deadly than moves like Clangorous Soul or No Retreat. If you find it obnoxious, then it can be countered. Either way, Everything in Pokemon has a counter, and Shell Smash is no exception.
So, yeah. Thanks for listening to my monologue and I look forward to hearing your replies
Here, we disagree with the idea that just because things have counters means they're healthy. I feel like in your post, there are a lot of misconceptions that indicate you haven't played much, so I recommend you start there. Resources
here can help you, and I'm sure that anyone would be happy to help you with battling or building a team (except me, I'm lazy.) Welcome to Smogon, hope you have a good time here.
