Bowser Jr.'s Mighty Megahammer
Mario starts off on a small metal platform and can only continue when he receives Yoshi. Yoshi can use his tongue to neutralize the hazards and move forward. The Comet Medal is on the second airship. After making his way through the obstacle course, Mario fights against Megahammer. Megahammer attacks by shooting Bullet Bills and using his hammers to slam the ring. Mario needs Yoshi to help him. To defeat the boss, Yoshi must swallow a Bullet Bill and shoot it at Bowser Jr.'s Megahammer's glassy parts 3 times, including the back part by using the Sling Star. After Mario defeats him, he obtains the Grand Star and is able to go to World 4: The Many Mysteries Of The Cosmos.
Megahammer's Daredevil Run
Erroneously scripted as "Megahammer's Daredevil Bash", this mission is available when the Daredevil Comet is in orbit. The Megahammer retains his attack pattern from before.
The Green Stars are all in Mission 1: Bowser Jr.'s Mighty Meghammer.
Green Star 1
Green Star 2
There are a few Fizzlits in this metallic planet, and two Bullet Bill blasters in the walls. There are some yellow platforms that disappear after a set amount of time. At the end of the planet, there is a glass sphere the player must break by making Yoshi eat Bullet Bills and spit them back out towards them. There will be a yellow and white platform, which the player will ride through the Gunner Path.
This path is filled with Undergrunt Gunners and Mines. At the end of the path, the player will need to kill the Fizzlits and flip the switch to continue. The player will need to also use a Bullet Bill to break the glass sphere blocking the exit.
Bullet Bill Planet
There is a Hammer Bro on this planet, along with several Bill Blasters. The player will have to break the glass dome covering the lever so they can progress.
This path is much shorter than the Gunner Path. There are a few mines scattered along the path. During the player's travels, two Airships will appear, one with a ? Block and the other with a Hammer Bro and a Comet Medal. The player will need to shatter the glass sphere at the end of the path to progress.
This is the planet where the player battles the Megahammer. It is shaped like a green and white ring with a few Sling Stars and some black and yellow segments that fall off after Megahammer smashes his hammers against the planet or shoots a Banzai Bill at it. There are also some Star Bits around the top of Megahammer. There is a huge Black Hole in the center of the planet; however, Megahammer is not affected by it.