Whimsicott (no surprise there huh).
It's really not that good in ubers lol. Arceus switching in on it says 'you lose'...but its priority stun spore and encore and its grass typing are really screw with a large part of the metagame.
Espeon too. Magic Bounce is the most underrated ability in the game imo, probably because people don't use it thoughtfully. It's excellent at shutting down those dang-nabbed deoxys-s leads as well as foretress, lugia, blissey, etc.
This is bad! Badbadbadbad! Bad for team plasma...or plasbad for short!