Mushroom Mayhem

Mushroom Mayhem is the first floor in Mario vs. Donkey Kong 2: March of the Minis. Mario and his Minis enter this floor after Pauline is kidnapped by Donkey Kong, beginning their quest to save her. In the background of each room, a rendering of Peach's Castle can be seen. A floor similar to Peach's Castle appears in the game as the sixth floor, Toadstool Castle. The various music tracks played on this floor are arrangements of the Mini Mario levels from Mario vs. Donkey Kong.

Most of this floor's levels feature Pink Blocks. Other level elements that appear on this floor include girders, Yellow Springs, Blue Springs, Spikes, conveyor belts, and elevators. The only enemies on this floor are Shy Guys, Piranha Plants, and Circus Kongs.

During the first battle against Donkey Kong in Room 1-DK, referred to as Boss Game 1, Mini Marios are loaded into a cannon, while Donkey Kong hides behind a wall with three windows. Occasionally, he appears behind one of the windows, during which the player can shoot him with a Mini Mario by tapping the "Shoot" button below the cannon. Donkey Kong attacks by slamming the ground, causing barrels and barbells to fall from above, which can be avoided by moving the cannon with the stylus. If a Mini Mario touches a barrel or barbell, it breaks. The player's number of Mini Marios during the boss battle is based on how many Mini Marios were led to the goal in the floor's previous levels. If all of the player's Mini Marios are destroyed, the game is over. After taking 6 hits, Donkey Kong is defeated and flees to Tropical Island.