Camerupt @ LeftoversWeezing @ Black Sludge
Bold Nature
Ability: Levitate
EVs: 200 HP/252 Defense/58 Special Attack
-Sludge Bomb
-Will-o-Wisp
-Pain Split
-Thunderbolt
Comes in on anything and takes relatively little damage, avoids Earthquake completely. It then proceeds to Will-o-Wisp you to reduce your damage to shards, going down to about 1/3-1/4 of its health and Pain Splits. Then it destroys you with Thunderbolt, which your meager Special Defense can't handle.
Quiet Nature
Ability: Solid Rock
EVs: 6 HP / 252 Atk / 252 SpAtk
-Yawn
-Protect
-Eruption
-Earthquake
Thunderbolt and Will-o-Wisp have no effect while Sludge Bomb is ineffective. Comes in, Yawns and stalls for HP recovery. Then it erupts until you're dead. (150 base attack + STAB hitting Weezing's mediocre Special Defense would probably 2HKO at worst).
For counters, it Yawns as they switch in and Protects on the subsequent turn. It then blasts away at your HP while you sleep (and hopefully stay asleep).