Good Way to take out Sylveon on Triple Battle?

Question

There's always a support of Fake Out or Snatch (to remove Wide Guard) right next to it, and I just can't stop it from screaming my Pokemon to death.
Only way I can think of is to knock it out in one turn by three strong attackers, but calculations show that not many Pokemon can do that, especially the ones viable in Triple Battle.
I have two supporters, Whimsicott and Meowstic, and four attackers, Gallade, Garchomp, Milotic and Granbull. None of them are strong enough to knock out that frigging pink dog-cat-whatever.

Need some help.
Willing to change my members if you guys make a suggestion.

Answer 1

Use a Pokemon with bullet punch like lucario,machamp or hitmonchan.Sylveon has 65 base defence so I believe it will be a OHKO.
Here is an example:
Lucario
Evs : 252 attack 252 speed 6 defence
Nature:Jolly
Ability:Inner Focus(for Fake Out)
Item:Lucarionite
Moveset:
Bullet Punch(for Sylveon)
High Jump Kick
Earthquake
Blaze Kick

Comments

Uh I already checked the calculations. Problem is HP 252 Sylveon isn't knocked out by anything less than Life Orb Bullet Punch Scizor. Mega Lucario with 252 attack still can't knock it out with one bullet punch...
I'm going to try Mega Gardevoir with Imprison, but thanks for the suggestion.

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Any Iron Head from Escavalier and Mega Metagross will OHKO standard Sylveon.