Ability: Inner Focus
EV's: Defence and Special Defence
Stratigy: Use Mean Look so the pokemon can't get away. Use Toxic to poision.
Use Confuse Ray to confuse. Use Super Fang to take consistant chunks out of their health. EV's in the defences so it can take hits. It's base speed is great so it does not need EVs there.
Gengar's Typing by itself kills this set