I see a LOT of Aron. Ferrothorn with Leech Seed beats it (but with a shred of health left), and Dual Chop from Haxorus is brilliant. If I don't have either of those, I usually have a Knock Off user who sacrifices himself in order to mortally wound Aron. In short, Aron almost always nabs one kill and also makes setting up incredibly risky while it's alive.
Never seen any of the others in well over 100 battles though.
REGIGIGAS is so CUTE.
My wifi occasionally acts up, but that's the only reason you'll see me disconnect. ;)