I love using eviolite Porygon2 in XY. It just. Doesn't. Die. It can face a Deoxys (Attack form), a rock or steel pokemon with some luck... But not Aegislash.
Those motherfuckers always win against it.
Yeah with STAB tri-attack
http://instantrimshot.com/
Link
VoidChimera
Porygon is made of pure hatred.
I love it.