Bowser Jr.'s Mighty Megahammer

Bowser Jr.'s Mighty Megahammer is the first mission of Bowser Jr.'s Fearsome Fleet in Super Mario Galaxy 2. The objective is to defeat Bowser Jr.'s Megahammer.

Mission
The player starts on a path with some disappearing platforms, Fizzlits, and Bullet Bills being shot out of Bill Blasters. Freeing Yoshi at the end of the path, Yoshi needs to eat a Bullet Bill and fire it at the large cage to destroy it, opening the way forward. The player then needs to activate a Lever Switch, which will cause a platform to begin moving and some Undergrunt Gunners to begin firing Bullet Bills that will home in on the player. Riding the platform, the player needs to avoid Space Mines and reach another Lever Switch that will activate the next platform. Partway through the path of the moving platform, the player needs to fire a Bullet Bill to break a large cage, then use the Sling Star behind it to reach the next path. Here, the player needs to grab a Bullet Bill and cross a large gap to reach a cage blocking a Lever Switch; there are flowers, but the player cannot use them when Yoshi is holding a Bullet Bill, so the player needs to Flutter Jump to cross the gap. Activating the Lever Switch will cause a platform to begin moving along a rail, and airships will begin coming out of portals and intercepting the platform's path. The player needs to jump over the airships and quickly return to the moving platform, followed by using a Bullet Bill to break another large cage. Afterward is the Launch Star that will send the player to the planet where Megahammer is fought.

Megahammer will attack by sending out Bullet Bills and Banzai Bills, along with attempting to smash the player with its giant mallets if the player is in front of it, or sending out a shockwave if the player is behind it. If the mallets hit a yellow and black striped block, it will disappear, creating a gap in the ringed platform. The mallets will also send out shockwaves. To damage Megahammer, the player will need to send back the Bullet Bills it fires at the three large, blue orbs on its body; two are in the front and one is in the back, which can be reached by using a Sling Star. Each orb takes two hits to fully destroy them, and once all the three orbs are destroyed, Megahammer's cockpit protection will forcibly open up and it will change tactics. Megahammer will slam both of its hammers down after firing some Bullet Bills, which the player needs to hold onto while avoiding the hammers' shockwaves. The player then needs to fire the Bullet Bill at the now exposed cockpit. A successful hit will crack the glass. Firing another Bullet Bill at the cracked cockpit will cause it to fully shatter. Once the glass shatters and Bowser Jr. is now exposed, Megahammer will start exploding and Bowser Jr. will flee, dropping the Grand Star, which can be collected by using a Sling Star.