Once upon a time in Bowser's Castle, Bowser was on his throne, complaining on how a certain plumber and his brother are always defeating him. At that moment, Bowser Jr., Kamek, and a Hammer Bro. come in and tell him about something called a Dimension Star that could help. Bowser laughs evily and the four set off.
After defeating the final boss, Bowser finally gets to the Mushroom Museam, and he beats Mario for once. Bowser grabs a fake Dimension Star, and all the bosses he beat in the game surround him, his son, and his two minions. Bowser looks at the screen as it irises to black, and as the words "THE END" show up, punching sounds and screams are heard.
- Bowser: He isn't so hot on jumping, but his fiery breath makes up for it. No need to unlock him.
- Bowser Jr.: A fireball spitter, and possibly the fastest runner and best jumper. No need to unlock him.
- Kamek: He can hover on his broom and shoot those shapes from his wand. No need to unlock him.
- Hammer Bro.: He can throw hammers (regular), fireballs (fire), iceballs (ice), and boomerangs (boomerang). No need to unlock him.
- Petey Piranha: The biggest in the game. He isn't so hot on jumping or running. He can slowen his fall and is the strongest character in the game. To unlock him you must beat the whole game twice.
- Koopa Troopa: The smallest in the game. He can duck into his shell and begin spinning, just like Shell Mario in NSMB. To unlock him you must beat the whole game once.
- Shadow Mario: Mario's dopplenagger with the same abilities as him in NSMB. To unlock him you must beat the game once with Bowser Jr.
- King K. Rool: Same as Bowser. Unlocked by clearing the game three times.
- The Toad Brigade: World 1's boss. A group of multicolored Toads which you fight seperatly. They will each use different attacks, so be careful.
- Yoshi: World 2's boss. Yoshi will flutter jump and ground pound, as well as try and eat you and spit you out in an egg. There is a little tyke on his back. When you hit Yoshi once, that little tyke gets into a bubble and floats around crying. While trying to get the baby back, any attack will defeat him.
- Donkey Kong: World 3's boss. A swinging gorilla who swings by. He will often try to make you're character slip on banana peels.
- Rosalina: World 4's boss. She has evil-seeking fireballs that shoot from her wand. Be careful!
- Princess Daisy: World 5's boss. She can summon Good Piranha Plants to help her fight you. She also has a flower-like boomerang attack, similar to a Good Boomerang Bro.
- Wario and Waluigi: World 6's bosses. You fight them sepereatly.
- Princess Peach: World 7's boss. Just like daisy, except she summons Good Koopa Troopas instead. Hit her with a Koopa Shell to make her dizzy, then attack her.
- Mario and Luigi: World 8's bosses, and the final boss. You fight them seperatly.