Donkey Kong does a quick headbutt above himself. DK's primary combo move due to its decent hitbox, very wide autocancel window, and convenient knockback scaling that allows it to be usable at a lot of percents against most of the cast. It is also a reliable kill option against midfallers like Sheik at percents when forward aerial won't combo. It's a useful air-to-air option in neutral, particularly as a tool to catch shorthops from characters like Sheik or Ganon who typically start their aerials as they fall.