I want him to have 252 attack EV's. I'm not sure if I want a choice scarf, life orb, leftovers, or choice band scizor either. I'm using him with a defencive rotom wash as my core
Regardless of whether you run Lefties, Life Orb, or Choice Band, (Scarf isn't recommended) you should probably run 252 HP / 252 Atk / 4 SDef