Whimsicott @ Life Orb
Ability: Prankster
EVs: 252 SpA / 4 SpD / 252
Speed
Modest Nature
- Moonblast
- Giga Drain
- Tri Attack
- U-Turn/Memento
OK so Tri Attack Whim is really awesome, it can revenge kill a lot of weakened scarfers and Set up Sweepers, and while it won't OHKO them it just cleans well and you basically can't outspeed it except for stuff like E-speed Luke (who resists anyway so), just some calcs on set up sweepers and Scarfers to show merit it has at revenging. Also run Memento if you want in last slot, doesn't matter.
On my phone, computer broken (sorry showdown frens) can't do calcs and am lazy so it does around 50% to 55% on Shao and Absol, 75 to 90 on Cloyster, (kills if -1) 45 to 50 on Haxorus, so it has some decent power. Also just shreks anything under 25% trying to kill you when your low on HP and you surprise them :)