Sableye @ Leftovers
Impish Nature (+Def/-Sp.Def)
Toxic First, then Confuse Ray. They get hurt more and more from Toxic while they hit themselves from Confusion.
If they can be hurt by Ghost Attacks, use Shadow Ball for STABed Power 80 Ghost Att(120 with 1.5 from STAB). If a Rock, Ground, or Water Pokemon show up, use HP Grass for 2x or 4x damage if they are a dual type like Swampert or Golem.
Protect if you want an extra turn for when they get hurt by Toxic.