Now with the mega evolution this baby wrecks...
Night Slash/Bullet Seed/Aerial Ace
Rock Blast is for Flying and Fire Types, your main weaknesses
Pin Missile/Arm Thrust is for STAB(Pin Missile is also to cover Psychic weakness)
Last slot is up to you to decide, Night Slash also covers Ghost(and Psychic ofcourse), Bullet Seed, like your other 3 moves, makes use of Skill Link and can deal with bulky Water types like Blastoise or Azumarill. Aerial Ace is maybe low on BP, but never misses, and covers bulky Grass Types as well as other Fighting types
This thing is OP with a 185 Atk BP...but his speed is not that great...maybe in a Trick Room he can deal quite some damage...otherwise you just have to hope that Heracross doesn't get hit with a Flying Type move