You should run Electivire A, since that is the best set.
It maximizes both of its offense potential and has good coverage moves. The nature and EVs are also best for this set.
Why not the other ones?
Electivire B can be used, but its moves and EVs are wrong. You should replace Ice Punch with Hidden Power [Grass] and the EVs should be 252 Sp. Atk / 252 Speed / 4 Atk and a Naive nature, so it doesn't lower its Atk or Sp. Atk. Also change the item to a Life Orb, so that you wouldn't be choice-locked.
Electivire C is alot like Electivire A, but its choice of moves do not have enough power. The elemental punches do not have much power and most experienced players aren't going to let you set-up with Power-Up Punch. If you really want a more powerful set-up moveset, use this set: Wild Charge / Ice Punch / Earthquake / Power-Up Punch. If you find that you're being walled by Ghost-types alot, then use Meditate instead of Power-Up Punch.
I hope I helped!