Boomsday Machine

Bowser Jr.'s Boomsday Machine is a castle-like boss who appears to be in the game Super Mario Galaxy 2. It is fought in a level of Bowser Jr.'s Boom Bunker. Bowser Jr.'s new ride is a fireball-spewing tower of death. The music heard during this battle is the same as in the Bowser Jr.'s Airship Armada battle. Strangely, Megahammer remains are found here, with scares the Toad Brigade.

Battle
There are ample Cloud Flowers around the area to grab. Ascending these and using them to get to the top of the tower is what this battle is all about. For the first round, Cloud Mario must run for one of the updrafts and spin to create cloud and ride it to the Cloud Flower refill. From here, he can long jump to the top of the Boomsday Machine with the help of a few cloud platforms. He should try to jump slightly diagonally to avoid the cloud-zapping yellow projectiles. Once Cloud Mario reaches the top of the tower, ground pound the glass. The second round is much like the first, but now the tower will attempt to vacuum the area, pulling the clouds out from under Cloud Mario's feet and covering the top of Bowser Jr.'s dome. If you get both close and high enough your cloud will not get vacuumed and you can wait for the electrical charge to go away. Cloud Mario should still be able to just long jump to the top of the tower in the same manner, he should just be ready to make a backup platform if he gets sucked up. In the final round, the tower goes mobile. This will makes Cloud Mario's climb to the top more difficult, since Bowser Jr.'s dome is much higher up, but the moving tank doesn't present that much more of a threat. He still needs to watch out for yellow projectiles, the spinning fire wheel and the vacuum attack, but Cloud Mario should really focus on climbing.

Once Cloud Mario reaches the top of an updraft, he needs to use the Cloud Flower refill to get to an even higher cloud tier. He should use long jumps to get to the distant cloud and he can score another refill. From here he can reach the brittle dome with his cloud platform recharge. Ground Pound the glass dome a third time to take Bowser Jr. out and claim a Grand Star.

Bowser Jr.'s Boomsday Machine is fought twice. The second being under the Daredevil Comet conditions (along with the rest of the level).