Well, since Xelac
alle posted Keldeo, here it is - the manliest super computer that has ever existed.
Metagross @ Choice Band
252 HP / 252 Atk / 4 Def
Trait: Clear Body
Adamant Nature
~ Meteor Mash
~ Bullet Punch
~ Pursuit
~ Earthquake
Metagross takes pitiful damage from Dragon Pulse and Psyshock / Psychic. To deal with 'Gross, Latias will have to pack HP fire, something that becomes more or less useless if we decide to go for rain (unboosted goes from 3HKO to possible 5HKO). And she's got to drop Roar, too!
Meanwhile; Meteor mash has a 68,75% chance to OHKO after SR; whereas a Pursuit will OHKO Latias while switching out after SR damage. Just like Latias, Celebi takes massive damage from both Meteor Mash (KO 30% of the time after SR) and Pursuit (68,75% after SR and switching). Heatrab gets OHKOed by Earthquake, no warnings, no questions asked, do not pass go, do not collect 200$. If taking out Heatran is critical, Metagross has a chance to kill it
while burned.
Metagross also forces Team 2 to pack a powerful defensive wall that resists Meteor Mash. Bulky waters not named Quagsire, Gastrodon and Seismitoad (lol) all get taken out by his lightning-weilding comrades; so their choices are somewhat restricted. Opposing steel-types usually share the same fate as Heatrab, unless they're a can opener with wings, but Jasmine and the Genie can handle that one.
Bullet punch allows Metagross to revenge fast threats on low HP thanks to the priority. His steel typing and mighty defenses let him tank those damned Outrages / Draco Meteors, alleviating our defensive necessities. On top of that, Metagross either resists or takes neutral damage from all priority attacks, which is a plus (but it's not like anyone needs priority attacks to revenge that 70 base speed).
Synergy-wise; Metagross takes ice and rock attacks for Thundy-T, while Thundy has 0 problem switching into ground attacks. He also takes neutral damage from bug, dark, fighting, resists flying and quad-resists psychic for Meloetta; and Meloetta's high special defense allow her to take the special attacks that will be aimed at Metagross' lower special defense.
Trick is also a possible option to cripple opposing walls; but I feel priority and coverage are more important for this team so far since Meloetta and Thundurs-T are pretty powerful wallbreakers already. Ice Punch is an option to nail dragons; but 2x effective Ice Punch deals equal damage to neutral Meteor Mash so NYAH.
Edit, status'n'such - Can't actually come in on Heatran because of Will-o-Wisp / Lava Plume. Metagross doesn't care about onion head's paralysis except for the hax, since outspeeding Ferrothorn isn't one of his main selling points anyway. Latias is his #1 bitch unless she carries HP fire, but then she can't stop Thundurus.
Edit 2, teammates - Metagross loves SR on the field, spikes off his side and paralysis support.
Metagross is totally not my favorite Pokémon, I swear.
Pic related: