Sheer Cold Scarftrio. Champ can't even switch, and you still outspeed at +2. You don't outspeed at +3, though.
Not sure what else to give it. Toxic (or maybe Sandstorm) for taking out sheddies? Life Gambit for Shuckles and other low HP mons? Splode? Lunar Dance? Memento? Obviously there's also boring old EQ and such.
Also, does Sturdy still block damage from OHKO moves, or is it just an auto-sash now?
It still blocks them.