I love Porygon2. It takes down the dragons in OU and takes their attacks like a boss.
Nature: bold if download, relaxed if analytic
EVs: 252 def, 252 sp.def, 4 sp.atk
Tri Attack: stab and hack of the gods.
Ice beam: to take down those Garchomps (in one hit)
Toxic: to stall what you can't kill
Recover: to last as as annoyance forever!