Bowser Jr.'s Fearsome Fleet

Bowser Jr.'s Fearsome Fleet is the last galaxy of World 3 in Super Mario Galaxy 2. Mario is fights Megahammer here, a new boss in the game operated by Bowser Jr. in a stage. Hammer Bros. can be found in the pre-boss area. Also, Yoshi can be found in this galaxy as well, considering that he is needed to defeat the mechanical giant.

First Platform Planet
There are a few enemies in this metallic planet, and two Bullet Bill blasters in the walls. At the end of the planet is a crystal Mario must break by making Yoshi eat Bullet Bills, and a big platform that takes Mario through some enemies that shoot more Bullet Bills at him.

Second Platform Planet
There is a Hammer Bro. in this planet, along with several Bullet Bill Blasters. After getting on a platform, Mario and Yoshi will have to avoid obstacles such as airships and Bullet Bills.

Megahammer Planet
This is the planet where Mario battles Megahammer. It is shaped like a ring with a few Sling Stars and some black and yellow segments that fall off after Megahammer smashes its hammers against the planet.