Ok so I just got a streak of 87 in super singles with my Cloyster team. The way I lost was stupid and embarassing (more on that below).
Cloyster @ focus sash
Garchomp @ lum berry
Ferrothorn @ leftovers
Cloyster is pretty cool. It's a bit like Scarf Darmanitan in that it can sweep many teams on its own really quickly. As you can see mine is mixed. Not sure whether it's actually better than pure physical but Surf having 100 accuracy is a nice bonus, and it can deal with defensively biased pokemon that shrug off my other moves (e.g. Cobalion 4). The evs are set to ensure I outspeed Scarf Terrakion after 1 smash (sadly I'm still outsped by Scarf Entei no matter how much speed I put in).
I've found the best pokemon to set up on are opposing set up pokemon, particularly Amnesia, Stockpile and Calm Mind. Those pokemon are stupid and think they can beat me if they can set up alongside me. Instead, I maximise my offences and speed, plus I still have my Focus Sash intact. I can't lose unless the opponent just happens to have two priority users in tow (but even then my other team members can finish up).
Garchomp serves as my status absorber. It may seem unorthodox, but with Lum Berry, Substitute, Thunder Wave immunity and its great speed stat, it can turn Will-O-Wisp spammers into set up bait. It also has great initial power in Earthquake if it needs to attack right away. Plus, Garchomp can abuse the Sandstorm that Cloyster hates. The evs maximise attack and speed. The remaining is put into Sp. Def rather than HP to ensure I can make 4 substitutes at full health rather than three. Hasn't mattered yet but you never know.
Ferrothorn can deal with Water and Steel types nicely which is important because Cloyster can't set up well against them at all. It also deals with Trick Room. It's the standard set so it brings the usual benefits to the team. The only downside is the fighting weakness, but it isn't that big of a deal usually (though I did have one annoying battle where the opponent lead with Fake Out Mienshao with Mach Punch Conkeldurr as back up). The evs focus on Sp. Def, but some Def investment is absolutely necessary because Ferrothorn struggles to keep its Substitute up against strong Earthquakes and X-Scissors without Def investment if it has no Curse boosts.
Certain steels can be troublesome to this team, especially Trick Room Bronzong (if Ferrothorn has died). It really all depends on the situation though.
How I Lost:
I lost mainly because I didn't check the first pokemon's moveset carefully enough, along with a retarded accidental misclick (in that I meant to click one move but missed and hit the other).
Battle 88 vs. Pilot Chand
I send out Cloyster, Chand sends out Honchkrow
I Shell Smash, Honchkrow Thunderwaves
Honchkrow Drill Pecks (Cloyster at 38 HP, Life Orb recoil), Cloyster fully paralysed
Honchkrow Sucker Punches, Cloyster dead
I send in Garchomp
I Substitute (Garchomp at 138 HP), Honchkrow Drill Pecks (sub broken, Life Orb recoil)
I Dragon Claw (Honchkrow at 20%), Honchkrow Drill Pecks (Garchomp at 29 HP, Life Orb recoil)
I Substitute (lol WTF), Honchkrow Night Slashs, Garchomp dead, Honchkrow dies to recoil
I send out Ferrothorn, Chand sends out Charizard
Charizard Fire Punchs (Ferrothorn at 13 HP), I Gyro Ball (Charizard at 60% with Iron Thorns damage)
Charizard Fire Punches, Ferrothorn dead (Charizard at 50% with Iron Thorns damage).
Ok, so firstly I Shell Smashed without seeing that Honchkrow 4 has Thunder Wave. If I'd switched in Garchomp then things might have turned out differently. After the Thunder Wave I left Cloyster in as a paralysed Cloyster is basically useless, and of course it was fully paralysed.
I chose to Substitute first with Garchomp because I thought Honchkrow might Sucker Punch, though it was probably a 50/50 chance between Sucker Punch and Drill Peck (note they have the same power). I then go to kill it with consecutive Dragon Claws, but then I literally miss the Dragon Claw button on the second attempt and use Substitute instead!
Of course, the opponent just happened to have a Charizard when Ferrothorn was my last hope. What is funny is that when I sent out Ferrothorn I actually thought to myself 'he is probably gonna send out a Moltres or a Charizard'. I must be psychic (or I've played enough to know that the subway is really good at putting you into worst case scenarios).
For the record, Chand's last pokemon was Zapdos. 2 of the Zapdos used in the subway have Heat Wave, so there's a chance I lost by a long shot. I'd say the Thunder Wave mess at the start was the true game decider. If I'd switched in Garchomp then, it could have beaten Honchkrow and then Cloyster could have set up on Charizard or Zapdos and won (assuming Zapdos didn't paralyze or evasion-hax me). I don't think the misclick changed anything (Garchomp was almost dead and I doubt a near dead Garchomp and Ferrothorn would have beaten Charizard and Zapdos, especially if Zapdos had Heat Wave).
I will be giving this team another shot in the future that's for sure, but not right now.