Bowser Jr.

Bowser Jr. is Bowser's ninth, and final son. He makes another appearance in Super Mario Galaxy 2, and appears in the final boss battles in Worlds 1, 3, and 5. In World 1, Mario only fights Gobblegut, his pet. In Worlds 3 and 5, he fights two machines operated by Bowser Jr., Megahammer and his Boomsday Machine.

World 1 Battle
Bowser Jr.'s Fiery Flotilla- Gobblegut's Aching Belly and Fiery Flotilla Speed Run

After Mario completes the rather short level in Bowser Jr.'s Fiery Flotilla, he will land on a brown planet, and Bowser Jr. will summon Gobblegut to fight Mario. Gobblegut will circle the planet a few times, and eventually he will charge headfirst into the planet, and that's when Mario should hit him. Gobblegut's weak points are his six pink bellyache bulges. Spinning all of these when Gobblegut charges into the planet (or spinning them in the air, which requires good aim) will cause him to explode and release the 1st grand star of the game.

The prankster comet requires to defeat Gobblegut in two minutes, and thankfully, Mario does not have to complete the level, though. The fight is the same in the prankster comet.

World 3 Battle
Bowser Jr.'s Fearsome Fleet- Bowser Jr.'s Mighty Megahammer and Megahammer's Daredevil Bash

This grand star requires the player to make extensive use of Yoshi, and is the only grand star which can be obtained by Mario and Yoshi. The level is much longer than Fiery Flotilla, and eventually, Mario should land on a ring-shaped planet with a few sling stars to get to the other side, and a few nests for Yoshi eggs. This time, Bowser Jr. attaches his pod to the body of a robot called Megahammer. Mario will have to have Yoshi first (from the egg on the platform, or from the level). Megahammer will launch Banzai Bills (Bullet Bills that stalk Mario) from his body, and Yoshi will need to eat them, and launch them back at the light blue domes on Megahammer (much resemblance to female breasts). Megahammer will launch two at a time, so it might be helpful to eat one, launch it randomly, then eat the other and aim. Megahammer will block some of the Banzai Bills with his hammers, so you can't hit him every time. The domes take two hits to break, and once Mario and Yoshi destroy the first two on Megahammer's front, they will need to take the Sling Star and will land on the other side of Megahammer. Yoshi will have to do the same thing, but, Megahammer creates a shockwave that damages Mario, and four Banzai Bills will shoot out instead of two. Yoshi must eat one, and shoot it at the single blue dome on Megahammer's back twice, however, once hit once, Megahammer will turn around, and Mario will have to take the sling star to the other side to repeat the process. After the back dome is destroyed, the battle will return to the front, and Yoshi should eat another Banzai Bill. Once in a while, Megahammer will slam his hammers on the ground, putting his head down and creating a shockwave. Yoshi should jump twice to avoid the shockwaves, and spit the Banzai Bill at the glass on Megahammer's head. This hit requires accuracy and timing, and one must do it twice in order to fully defeat Megahammer. After Megahammer is destroyed, the Grand Star will appear above the middle of the ring. Carefully, without falling through the holes in the ground that Megahammer created, Mario must use the Sling Star to collect the Grand Star.

The prankster comet will require Mario and Yoshi to defeat Megahammer in a daredevil run (having only 1 slice of health when fighting). Thankfully, Mario will not have to go through the level; he will land on Megahammer's planet when he selects the star.

World 5 Battle
Bowser Jr.'s Boom Bunker- Bowser Jr.'s Boomsday Machine and Boomsday Machine Daredevil Run

This grand star makes use of the Cloud Flower, and although the objective is simple, executing it is harder than it looks. After completing the level, Mario will land on the large Battlefield planet. Bowser Jr. will control a castle turret-looking thing called his Boomsday Machine, which also has firebars that revolve around the battlefield. Mario will have to grab a cloud flower, watching out for the firebars, and make clouds in one of the four updrafts around the battlefield. When he is high enough, he should grab another cloud flower, and make clouds towards the top of the Machine. Mario needs to get on the glass on top of the Boomsday Machine and ground pound it. He needs to do it three times, and each time becomes increasingly harder. For the second time, he must be aware of the yellow electric balls that launch out of the Machine, which will destroy his clouds. When the machine does this, it will have an electric shield, impervious to a ground pound, and it will send a draft of wind outwards, pushing clouds away from it. On the third hit, the machine grows in height, and reveals traction wheels to move. Mario will need to make more clouds higher (there will be more cloud flowers higher), and ground pound it a third time, being aware for all the dangers from previous hits. After this, the Boomsday Machine will explode revealing the grand star.

For the prankster comet, Mario will have to defeat the Boomsday Machine with the daredevil conditions, and he will have to go through a shorter version of the level with the daredevil conditions as well. This is most likely the hardest prankster comet for Bowser Jr. fights.

Personality and Traits
Bowser Jr. is much like his father; he despises Mario and the Mushroom Kingdom, and does his best to capture Princess Peach. He does appear to be a bit unwise by putting glass as his targets on his final boss battles, which shows that he still has much to learn. He does appear to be very loyal to Bowser, saying before the Boomsday Machine fight, "My dad's gonna get angry if I let you get another grand star". Throughout the Mario series, he appears to be Bowser's favorite son.