I'm thinking
Nature: Relaxed (+def -spd)
Ability: Iron Barbs
EVs: Def and Attack
Item: Rocky Helmet
-Curse
-Gyro Ball
-Stealth Rocks
-Sucker Punch/ Bulldoze/ Payback
If you are using it for double battles I would go with Bulldoze and pair it with a Trick Roomer but if not Sucker Punch or Payback will really start to hurt after a couple Curses