Gigaton Hammer inflicts damage. The user cannot select Gigaton Hammer in succession unless the move failed. If the player attempts to use Gigaton Hammer twice in a row, they will be prevented from doing so, and will be allowed to select another move. Once another move is used, Gigaton Hammer can be used again.
If the user cannot select another move (due to Choice items or having no other usable moves), it will use Struggle every other turn.
Instruct and Sleep Talk allow Gigaton Hammer to be used twice in a row. Encore allows Gigaton Hammer to be used twice in a row, but on subsequent turns of the Encore the user will be forced to Struggle.