Butterfree

Butterfree @Life Orb
-Sleep Powder
-Bug Buzz
-Roost
-Tail Wind
Compound Eyes, Timid
252 Sp.Atk, 252 Spd, 4 Def

I have had the most incredible success with this Butterfree. I was honestly surprised myself by how useful this thing is. Believe it or not, this is NOT a lead Butterfree! I just have it sitting around on my team, lookin' pretty and tasting blood with its feet (cause, y'know, butterflies taste with their feet...)!

Anyway, Life Orb helps to boost its already respectable Bug Buzz damage output, while Sleep Powder helps to shut down threatening targets. Once they're snoozing, I like to put up a Tail Wind in preparation for an unplanned early wake up or a switch, and Roost up back out of Stealth Rocks' kill-range if I'm within it. Being that Butterfree is immune to Ground attacks and boasts a monster-resistance to Fighting attacks, it's actually a very valuable switch-in, and Roost has proven to always keep Rocks at bay, so long as I'm wise with when I switch in and who I switch in against.

This Butterfree sweeps teams.

P.S. If you're Butterfree has 31 IVs in HP (or any odd number of HP IVs, I think I can assume...) do NOT invest a point in HP! As long as Butterfree's HP is ODD, it can survive TWO Stealth Rock switch-ins, Sleep Powder, and then Roost back up out of Stealth Rocks' kill-range! MAGIC!