Here are the Tyranitars:
Pokémon: Tyranitar. Item: Roseli Berry (this weakens a super-effective fairy type move).
Ability: Sand Stream (the greatly raises your Sp. Def and hurts Xerneas a little bit for 5 turns).
EVs: 240 HP / 18 Def / 252 SpD.
Nature: Careful (+Sp. Def, -Sp. Atk).
IVs: Max.
- Toxic (use this as soon as you start the battle with Xerneas).
- Snarl (you could use this after protect to weaken Xerneas so your other Pokémon have a chance of winning).
- Protect (use this after toxic).
- Stone Edge (if you want to, you can use this to speed up the process of toxic).
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Pokémon: Mega Tyranitar. Item: Tyranitarite.
Ability: Sand Stream.
EVs: 252 HP / 6 Def / 252 SpD.
Nature: Careful (+Sp. Def, -Sp. Atk).
IVs: Max.
- Snarl (use this or stone edge after toxic).
- Stone Edge
- Toxic (start the battle with this).
- Iron Head (a super-effective steel type move for Xerneas that won't miss. Attack power isn't too great though but it's 80).
Here's the Xerneas the T-tars want to survive:
Pokémon: Xerneas. Item: Power Herb.
Ability: Fairy Aura
EVs: 252 HP / 6 Def / 252 SpA.
Nature: Modest (+Sp. Atk, -Atk).
IVs: Max.
- Geomancy
- Dazzling Gleam
If Dazzling Gleam was Moonblast it would be over for you. Things would also be bad if Xerneas used Geomancy twice (actually it would probably be better but, watch out for Z-Geomancy). Now, here's a replay to show that the T-tars can survive (it also shows what you should do with the T-tars). And this replay shows what mega T-tar can really do. Don't worry about the T-tars never winning, as long as they used toxic Xerneas will eventually faint when your other Pokémon attack/stall (unless T-tar is your last Pokémon :/. But the 1st T-tar actually beat Xerneas).
I hope I helped!
