Megahammer is the final boss of World 3 of Super Mario Galaxy 2.You encounter him at the end of the level Bowser Jr.'s Fearsome Fleet. It is a robot whose most distinguishing features are its giant hammers for hands, which is among it's attack methods. It's head is actually Bowser Jr.'s robot cockpit, which is attached to the body at the start of the battle.
BattleEditIt's main attack is launching Bullet Bills and Banzai Bills at the player, who has to have Yoshi swallow the Bullet Bills and spit them back them at three blue orbs. There are two of the said orbs located on its chest and one is on it's back. It can also do a shockwave attack and can pound it's hammers into the ground. It's second phase is relatively similar when it comes to attacks. When Megahammer shoots it's Bullet Bills, have Yoshi swallow one, and when the robot attacks with it's hammers, spit it back at its head. Defeating it earns you the third Grand Star.
- Megahammer was originally going to be called Mallettoid.