Threat list:
Abomasnow - Slowbro usually takes it out, Wood Hammer isn't too detrimental to Slowbro's health.
Azumarill - Slowbro comes in and scares it with Scald, or finishes it with Psychic. Hazards love to destroy Azumarill.
Blissey - Forretress uses Blissey as set up bait, hazards and Jirachi usually scare it away and kill it, if not Gliscor who is for all practical purposes immune to basically every move Blissey has.
Breloom - Gliscor, Slowbro doesn't take too much from Seed Bomb if it's carrying it, if it's running Stone Edge Slowbro can just laugh it off.
Bronzong - Slowbro and Celebi, Celebi can usually use it to set up.
Celebi - One of the biggest threats to my team, I can usually get around it with Jirachi and a few other attacks. Really need a better way to defeat it.
Chandelure - Sucks. Blissey can beat it, none of them run Taunt or sub for some reason.
Chansey - Same way with Blissey, but Seismic Toss-only varients are just lol'd away by Celebi. Forretress uses it as set up bait, while Chansey is still fairly weak to hazards.
Cloyster - Slowbro. There's nothing I could say about Cloyster except for that it's ****** and no one should ever use it. Good day, sir.
Conkeldurr - Mostly Slowbro, had to switch Ice Beam for Psychic to check Conkeldurr better.
Darmanitan - Slowbrooooo, again. Scald scares the **** out of Darmanitan, it's really not much of a threat.
Deoxys-S - Deoxys-S is usually one of those bait-switch kind of things, bait out Superpower for Blissey, switch to Slowbro, continue to go back to Blissey and scare it off.
Dragonite - Slowbro takes the DD varients, none of them like burns. Special rain varients can be taken out by Blissey, and band can't really do much to Slowbro outside of Outrage, which can be slacked off to stall out.
Espeon - I just ignore whatever moves its got and just attack away, trying to nab screens before they get set up, and CM BP is usually used as Celebi bait. Jirachi doesn't fear any of the sets really.
Excadrill - Gliscor and Slowbro, even Celebi to anything that doesn't carry X-Scissor. Gliscor mainly, obviously.
Ferrothorn - Slowbro is a sure 2hko with Flamethrower, can't do anything to subbed Gliscor, Forretress spins everything it has and sets up on it.
Forretress - Slowbro and Forretress are my answer to enemy Forretress, pretty self-explanitory as to why.
Gastrodon - I usually Toxic these and hope for the best, they can't do much to me either, though, so I don't worry too much.
Gengar - adfasgadfga;jd, SubDisable screws with me. Again, would love to find a better check to this. I don't even remember how I've handled them in the past.
Gliscor - Slowbro again. .-.
Gorebyss - I haven't seen one yet, smash pass just isn't very common in OU I guess. Jirachi could handle it I guess, with Body Slams.
Gyarados - Slowbro burns, Celebi sets up, what else could there be?
Haxorus - Slowbro and Gliscor can usually take it out. Jirachi can paralyse it if needed.
Heatran - Slowbrooooo .-.
Hippowdon - Slowbro/Celebi
Hitmontop - Slowbro
Hydreigon - Blissey can take all the mixed sets hits and still make it switch out or die of toxins/seismic toss.
Infernape - Slowbro, band U-Turn is still Regenerated off.
Jellicent - Celebi sets up NP and has fun.
Jirachi - CM Celebi screws with me, but otherwise I just use Gliscor.
Landorus - Slowbro can take it and scare it away.
Latias - See: Latios (**** trick)
Latios - See: Latias (**** trick)
Lucario - Slowbro and Gliscor take it, Celebi can usually scare it off too. Same with Jirachi.
Machamp - Slowbro - the classic Machamp counter.
Magnezone - Gliscor, Blissey, you name it. Celebi sometimes too.
Metagross - Celebi and Slowbro take it out.
Mew - ...Which set? Too many T-T
Mienshao - Slowbro
Ninetales - Blissey, Slowbro for non energy ball varients.
Politoed - Celebiiiii
Porygon2 - Blissey and Slowbro can status and wear it out, Celebi sets up on it.
Quagsire - Celebi
Reuniclus - Celebi
Rotom-W - Celebi, Gliscor takes all choiced sets 1v1 if it decides to switch into a susb.
Salamence - Slowbro can take it, I've only tested against one Salamence, however.
Sawsbuck - Jirachi and Celebi anybody? Gliscor if Megahorn is used.
Scizor - Slowbro KOs it on the switch with Flamethrower usually, they just love thinking that I'll switch out on their Swords Dance, too.
Scrafty - Slowbro/Gliscor/Jirachi
Sigilyph - the definition of setup bait, doesn't like being paralysed no matter how good of a status absorber it is.
Skarmory - Slowbro and Celebi
Slowbro - Celebi... and Slowbro?
Starmie - Celebi, Blissey doesn't fear it at all either.
Swampert - Celebi...?
Tangrowth - Celebi.
Tentacruel - Celebi? Celebi. And Gliscor. And Jirachi. And Forretress. Blissey, too. Slowbro sometimes even.
Terrakion - Slowbro takes all the sets minus band's X-Scissor, and so does Celebi.
Thundurus - JIRACHI, Blissey also takes it out fairly well.
Tornadus - Doesn't like switching into anything, can't trick specs on Blissey, it forces me to switch to Blissey a lot but other than that Jirachi can handle it.
Toxicroak - Gliscor, anybody? Slowbro takes it down too.
Tyranitar - Usually just wears itself out, Jirachi, Slowbro, Gliscor, and Celebi all kind of make it scared.
Vaporeon - Celebi bait.
Venusaur - hmphphs, let something take a sleep powder, usually paralyse it or something of that nature.
Victini - Hazards, it usually tries to force Forretress to switch first turn, but I just pain split as Sturdy activates and all is well, then go into Slowbro.
Virizion - Jirachi
Volcarona - Blissey? It usually doesn't get to set up, so I don't know.
Whimsicott - Lol.
Wobbuffet - Ehh.... I usually just go with whatever sounds the least threatened by Encore at the time.
Zapdos - uhh... Haven't seen a single one.