The Big Hammer Attack can only be used when Amy has Knuckles as her partner. With Knuckles's influence, Amy's Hammer Attack is automatically transformed into the Big Hammer Attack.
When performing the Big Hammer Attack, Amy pulls out an oversized and massive version of the Piko Piko Hammer and whacks the opponents in front with enough force to create small tremors and break metal barriers that are otherwise invulnerable to Amy's attacks. However, the Big Hammer Attack takes much longer to be executed than a regular Hammer Attack, and also leaves Amy open and immobile for a longer period. It is therefore not advisable to use the Big Hammer Attack when fighting several enemies at once.