Metagross @ Choice Specs
Nature: Modest
EV's: 124 HP, 252 SpAtk, 132 Speed
~ Psychic
~ Hidden Power Fire
~ Grass Knot
~ Shadow Ball / Explosion
I think few people realize that Metagross has 95 base special attack, which is the same as Tyranitar's, who is very viable as a special attacker. Metagross has just enough special moves to surprise and defeat its common counters like Rotom, bulky steels, bulky waters, and bulky grounds.
The first 3 moves are no-brainers. Psychic is your main STAB which hits most of Metagross' common switch-ins for neutral damage and scores a 2HKO on most of them. Hidden Power Fire is needed to hit various Steel types. Grass Knot covers Water and Ground types in one slot. The last slot can go to either Shadow Ball or Explosion. Shadow Ball hits Rotom harder than Psychic, but it won't OHKO, and is your best move against various Psychic types such as Cresselia, Latias, Celebi, etc... However, if Blissey starts walling you after finding out you're carrying Choice Specs, you can Explode on her. Note that Flash Cannon is NOT used because most counters to physical Gross resist Meteor Mash.
The EV spread is very simple: you obviously want max special attack, and 132 speed EV's gives 208, enough to outrun 4-speed Suicune so you can 2HKO it with Grass Knot before taking a hit if it switches into you. Feel free to run less speed in favor of HP if you don't care about Suicune. HP Fire decreases your SpAtk and Speed by 1 point, but I've already taken that into all calculations.
Damage calculations:
Rotom-Appliance, 252 HP, 0 SpDef:
Psychic: 474 Atk vs 250 Def & 304 HP (90 Base Power): 184 - 217 (60.53% - 71.38%)
Shadow Ball: 474 Atk vs 250 Def & 304 HP (80 Base Power): 218 - 258 (71.71% - 84.87%)
Swampert, 252 HP, 0 SpDef:
Psychic: 474 Atk vs 216 Def & 404 HP (90 Base Power): 211 - 250 (52.23% - 61.88%)
Grass Knot: 474 Atk vs 216 Def & 404 HP (80 Base Power): 504 - 596 (124.75% - 147.52%)
Skarmory, 252 HP, 0 SpDef:
HP Fire: 474 Atk vs 176 Def & 334 HP (70 Base Power): 272 - 320 (81.44% - 95.81%)
Forretress, 252 HP, 80 SpDef:
474 Atk vs 176 Def & 354 HP (70 Base Power): 544 - 640 (153.67% - 180.79%)
Hippowdon, 252 HP, 88 SpDef:
Psychic: 474 Atk vs 202 Def & 420 HP (90 Base Power): 228 - 268 (54.29% - 63.81%)
Grass Knot: 474 Atk vs 202 Def & 420 HP (120 Base Power): 404 - 476 (96.19% - 113.33%)
Gliscor, 252 HP, 0 SpDef:
Psychic: 474 Atk vs 176 Def & 354 HP (90 Base Power): 261 - 307 (73.73% - 86.72%)
Suicune, 252 HP, 0 SpDef:
Grass Knot: 474 Atk vs 266 Def & 404 HP (100 Base Power): 256 - 302 (63.37% - 74.75%)
Vaporeon, 188 HP, 0 SpDef:
Psychic: 474 Atk vs 226 Def & 448 HP (90 Base Power): 204 - 240 (45.54% - 53.57%)
Gyarados, 156 HP, 0 SpDef (BulkyGyara):
474 Atk vs 236 Def & 370 HP (90 Base Power): 195 - 229 (52.70% - 61.89%)
Celebi, 252 HP, 0 SpDef:
Shadow Ball: 474 Atk vs 236 Def & 404 HP (80 Base Power): 230 - 272 (56.93% - 67.33%)
Bronzong, 252 HP, 96 SpDef:
HP Fire: 474 Atk vs 292 Def & 338 HP (70 Base Power): 164 - 194 (48.52% - 57.40%)
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