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As far I know, the Mega Heracross have Skill Link ability that allowed you hit least 5 times with multi attack moves.
Heracross have gain access to multiattack moves like Arm Thrust, Bullet Seed, Furry Attack and Pin Missile. Heracross can also gain Rock Blast as egg move.
The Mega Heracross is pretty much Atatatata, Oraoraora or Mudamudamuda type pokemon.