While charging such an attack on the ground, players can cancel/store the charge by shielding, performing a grab, or tapping left/right on the control stick or d-pad to immediately roll out of the charge. If they are in the air while in their charging state, cancelling it with a shield or grab button will make them cancel it with an air dodge instead.
Due to its buffer system, charge-canceling Giant Punch in Brawl will result in Donkey Kong performing an air dodge if the input is entered late into the charge animation.
List of moves that can be charge-cancelled
Samus is the only character who cannot charge cancel in midair, since Charge Shot cannot be charged in midair. Both Mewtwo and Lucario's auto-charge specials are also the only ones who continue charging at max charge unless cancelled or fired during that period, as opposed to automatically stopping like everyone else.