This is a little different and works best with a pokemon before it that used Substitute and Baton Pass. It can work alone, though.
Toxicroak (M) @ Leftovers
Trait: Dry Skin
EVs: 4 HP / 252 Atk / 252 Spd
Adamant Nature (+Atk, -SAtk)
- Focus Punch
- Sucker Punch
- Poison Jab
Ok, so I didn't put E.V.s into Sp.Def. because Toxicroak isn't going to stand up to a Psychic type that has Calm Mind, even with the Sp.Def. boosting.
If you haven't been baton passed a substitute, set one up. That is what sets up Focus Punch. Sucker Punch and Poison Jab seem pretty obvious, Sucker Punch for the Psychics and Poison Jab for the STAB.
I know some of you want to run Drain Punch over Focus Punch, but with Substitute, Focus Punch works (and Substitute provides Leftovers healing/Dry Skin healing).
Pretty deadly if used well, if you have any suggestions, please tell me.