"The guy who bashed Zygarde" pointed out that it is not an immediate threat and whatever it can do some other dragon in OU can do better and thus it couldn't be ranked higher than any other dragon besides normal Kyurem and Kingdra. I still think it's C+ material, unlike Cloyster who doesn't really face any competition because it is the best Shell Smasher. Can you honestly say Zygarde is the best DDancer or Swords Dance+Extremespeed user?
You meant Dragon Dance?
And no, Zygarde is unique since
no other Dragon can do what it does, which I'm pretty sure I said multiple times already. Garchomp has better offensive stats, but does not know Dragon Dance. The same applies to XZard and Dragonite, but their different typings differentiate a lot between them. Coil faces no competition whatsoever from anything else in OU. And while calling Zygarde "the best Dragon Dance user" or "best Extreme Speed user" is admittedly a stretch,
but I can honestly say that Zygarde does have its advantages over even Mega Charizard X, much less Dragonite, when it comes to Dragon Dancing, a role which you supposedly say it is outclassed in.
As for Cloyster, even if it is the best Shell Smasher (I say if because Barbaracle isn't actually looking too bad at this point), we still have to look at its raw ability. Even after a Shell Smash, Cloyster doesn't exactly KO everything, as you yourself listed multiple examples of Pokemon that can survive. But that is a trait all sweepers have, they need stuff weakened, right? The problem with Cloyster is that it
needs stuff weakened when it starts its sweep, since it simply cannot take a direct hit (or two, counting possible priority) to save its life.
It's notable because all of Cloyster's moves (besides Razor Shell which I think it's inferior to Ice Shard save for very specific scenarios) don't make contact and Skill Link Rock Blast is definitely a better move than Stone Edge. Every single Ground or Rock type sweeper, such as Garchomp and Tyranitar, does have contact moves (Dragon Claw, Outrage, Crunch) so a bad prediction can mess them up. Cloyster never has to worry about that. It's a small but important advantage.
Usually, being affected by Iron Barbs / Rocky Helmet / any contact-related item or ability hardly affects a Pokemon's ranking, so Cloyster shouldn't get much merit for simply avoiding those. I mean Talonflame and Mega Charizard X make contact practically all the time but they couldn't give less of a shit about the likes of Ferrothorn or Volcarona or whatever crazy Rocky Helmet wielder they happen to pass. I've already stated before, since Cloyster is a multi-hit attacker, not making contact is
what is to be expected, because if it did make contact Cloyster's threat level would be heavily nerfed. As I said, it isn't so much an "advantage" as "dodging the bullet".
Another minor nitpick, but Skill Link Rock Blast is a better
coverage move than
non-STAB Stone Edge.
That makes them checks, not counters. Everything has checks, even monsters like Mega Lucario. Even then, calling Gyarados a check is a huge stretch since it definitely can't take a Rock Blast on the switch, even factoring Intimidate. As for Azumarill, Cloyster actually beats the Belly Drum variants since Aqua Jet won't do jack and Azumarill will certainly not try to boost on Cloyster. A healthy CB Superpower Azu can beat it, but at the cost of taking major damage and becoming set-up bait itself after that.
And if Cloyster runs Life Orb:
+2 252+ Atk Life Orb Cloyster Rock Blast (5 hits) vs. 252 HP / 0 Def Azumarill: 375-450 (92.8 - 111.3%) -- guaranteed OHKO after Stealth Rock[/i]
Thing is, Rotom-W and Manaphy can counter Cloyster (switch in, survive +2 attack, OHKO). Gyarados is a better Cloyster check than counter, but it can still stop a Shell Smashing Cloyster on the switch and Mega evolving to remove its Rock weakness and retaliating, and Cloyster risks a lot by not Smashing against whatever Pokemon it is out against, as it won't get the chance to do so again if it takes any unecessary damage.
Belly Drum Azumarill can survive Rock Blast even with less HP EVs due to Sitrus Berry activating in the midst of the
multi-hit move (would you consider this a disadvantage?) and retaliate with Play Rough, which can stand a good chance to KO with -1 Def plus any possible damage Cloyster might have taken (which I find you seem to have left out a lot in your arguments and calcs, as
Treecko has already pointed out).
Again, this depends whether you're running Life Orb or not. It should be obvious by now that non-LO and LO Cloyster play very differently because the former can survive many revenge killing attempts but the latter earns many notable KO's
These do not play differently, the item choices only vary the appropriate responses, otherwise Cloyster plays
exactly the same: set up late game, weaken bulky Waters and Steels, don't switch in on anything.....one of Cloyster's biggest flaws is that it cannot afford to take any sort of damage pre-sweep, so that means you not only have to get rid of hazards and what not, but Cloyster can hardly contribute defensively at all, while every other setup sweeper can at least switch in on something without completely blowing their chances at sweeping.
+2 252+ Atk Life Orb Cloyster Icicle Spear (5 hits) vs. 252 HP / 0 Def Aegislash-Shield: 160-195 (49.3 - 60.1%) -- approx. 99.6% chance to 2HKO after Stealth Rock and Leftovers recovery
The Aegislash can still King's Shield to avoid the 2HKO, and trying to predict that and going for Shell Smash is, as you'd understand, incredibly risky.
You have presented me with several one-sided scenarios (a crippled Cloyster vs perfectly healthy pokemon) and yet despite this Cloyster can still hold its own. Now imagine what a properly played Cloyster with team mates who can open the doors for a lategame sweep is capable of.
Crippled? Every single scenario I've listed so far is of a 100% health Cloyster with +2 offenses & -1 defenses, pretty much the best case scenario for Cloyster by far. If Cloyster cannot even defeat these Pokemon while at full health, it kind of says a lot about the limits of its sweeping capability already.
One thing to always keep in mind is that Skill Link Icicle Spear has about a 30% chance of scoring at least a critical hit on one of the 5 hits, which will turn many 2HKO's into straight OHKO's
The crits thing was already accounted for in Gen 5, yet it didn't make Cloyster much more of a threat since it was like a very ocassional extra 10-15% damage that didn't really make or break any of its solid checks / counters. Now consider that crits have been nerfed, and I highly doubt most of the Cloyster responses would be subject to a OHKO.
The problem here is that you're only talking about "Cloyster" and not "Cloyster running X variant of Shell Smash with Y team mates who can deal with X can't beat".
First off, what X variant of Cloyster? All run Shell Smash, Icicle Spear, and Rock Blast, so chances are if you resist Ice you already has a good chance to stop a Cloyster sweep. Also, the "teammates backing Cloyster up" argument applies for everything, even, you know, Zygarde.
The things in Cloyster's way are really no more numerous or significant than every sweeper's annoyances, ranging from priority to Prankster, to walls. Just like Rotom-W is a thorn in Cloyster's side so is Mandibuzz in Aegislash's. Just like Cloyster hates Vacuum Wave Garchomp hates Ice Shard. Just like Cloyster is crippled by Prankster WoW from Sableye so is virtually every non-fire type sweeper.
Cloyster suffers the additional issue of "transforming into a glass cannon when it sets up". So what if Cloyster can now OHKO or 2HKO everything on the opponent's team, those Pokemon that Cloyster fails to OHKO are often sufficient in stopping the sweep, which is a lot to ask for when you consider most setup sweepers just need their counter(s) sufficiently weakened, rather than trying to whittle everything on the opponent's team to make sure Cloyster nets a kill every turn (which it must). Cloyster may have a massive Defense stat, but it contributes virtually nothing defensively and must be kept at the back until late game, or it won't expect to get more than one KO. Saying it can KO something and heavily weaken another is synonymous to pretty much every other setup sweeper, except they can actually switch into stuff and ocassionally take some damage.
As the best (and only) Shell Smasher in OU it has a niche no other pokemon has, which alone justifies a B- rank at worst. It's not that mono-dimensional because as illustrated Sash, LO and King's Rock variants play differently, as well as Razor Shell and Ice Shard ones.
The items do not dictate Cloyster's style of play, merely its responses (at best). There's a reason why there is only one Cloyster set: every Cloyster plays the same: Shell Smash late game, which is pretty one-dimensional if you ask me, so while it is a unique niche it is highly predictable (hell, even Talonflame can run a competent specially defensive set that uses Bulk Up and priority Roost!) and thus relatively easy to stop. Cloyster can hardly contribute early game or even mid game. Shell Smash is still a niche, but one that is very easy to see coming.