Shame that Amoonguss didn't make it as Meloetta's counter. Anyway, my suggestion for Team 2's second member, and Celebi's teammate is
Tyranitar @ Choice Band
156 HP / 252 Atk / 100 Spe
Adamant nature
~Crunch
~Stone Edge
~Pursuit
~Superpower
Going straight into weather, because:
A) Tyranitar eats Lati@s, and Chans/Blissey for breakfast.
B) Celebi will use Thunder Wave, spread paralysis around, and make everything slower than Tyranitar.
C) The list of things that can take 2 Stone Edge or Superpower or Crunch is essentially made up of Fighting , Water or Ground types, which Celebi can switch into fairly well.
From top to bottom, the list of stuff that can take hits from CB Tar are Hippowdon, Hitmontop, Donphan, Milotic, Wish-CM Jirachi, Tangrowth, Swampert, Suicune... all of which Celebi can easily switch into, and completely wreck.
Defensively, the two cover each other pretty well. Tyranitar can take Fire, Flying and Ice attacks all day long, while Celebi can handle Fighting, Ground, Water and Grass attacks. And Bug attacks...well Scizor takes 79.9% damage *minimum* from CB Stone Edge, and is then outsped, so it's forced to use Bullet Punch to do anything. I know you're not supposed to assume SR, but, if it is on the field, Scizor will die to the second entry. Nothing else of note uses U-Turn. Well maybe Landorus-T.
Tyranitar @ Choice Band
156 HP / 252 Atk / 100 Spe
Adamant nature
~Crunch
~Stone Edge
~Pursuit
~Superpower
Going straight into weather, because:
A) Tyranitar eats Lati@s, and Chans/Blissey for breakfast.
B) Celebi will use Thunder Wave, spread paralysis around, and make everything slower than Tyranitar.
C) The list of things that can take 2 Stone Edge or Superpower or Crunch is essentially made up of Fighting , Water or Ground types, which Celebi can switch into fairly well.
From top to bottom, the list of stuff that can take hits from CB Tar are Hippowdon, Hitmontop, Donphan, Milotic, Wish-CM Jirachi, Tangrowth, Swampert, Suicune... all of which Celebi can easily switch into, and completely wreck.
Defensively, the two cover each other pretty well. Tyranitar can take Fire, Flying and Ice attacks all day long, while Celebi can handle Fighting, Ground, Water and Grass attacks. And Bug attacks...well Scizor takes 79.9% damage *minimum* from CB Stone Edge, and is then outsped, so it's forced to use Bullet Punch to do anything. I know you're not supposed to assume SR, but, if it is on the field, Scizor will die to the second entry. Nothing else of note uses U-Turn. Well maybe Landorus-T.