Costume Mario

Costume Mario is the form Mario takes after eating a Mystery Mushroom in Super Mario Maker, allowing him to transform into numerous Nintendo and third-party characters and objects. Upon scanning certain amiibo onto the Wii U GamePad's, an 8-bit version of the amiibo character will be unlocked in the level editor, allowing the player to use it any time from then on without having to scan the amiibo again. In addition to amiibo characters, Mario can also transform into certain objects, such as a ? Block. Costumes can also be unlocked through the 100 Mario Challenge mode, including characters which have amiibo unlock conditions. According to Nintendo's website, nearly every confirmed amiibo is compatible, except the Mii Fighters. There are a total of 99 costumes in the game.

Costume Mario functions the same as Super Mario, but with Small Mario's physical stature (except Mega Yarn Yoshi, Charizard, Mewtwo, Lucario, Greninja and Sonic, who are slightly larger). While Mario wears a costume, he cannot wear any Shell Helmets. In addition to appearance, various sound effects may also be changed to reflect the character, such as the jumping sound effects and "Course Clear" fanfare. The power-up sound effect may also be replaced by a different sound effect from the character's home series. Pokémon series costumes are notable for lacking special sound effects, instead using the standard Super Mario Bros. sounds. Each character has a unique pose if the player presses and holds. Toad's message after finishing the 10 Mario Challenge and the easy mode of the 100 Mario Challenge also varies depending on the appearance of the player. Mario can only transform into Costume Mario in the Super Mario Bros. style of the game.

The costumes do not follow the graphical limitations of the NES. Most of them are designed to follow the character's official designs, usually using more than 3 colors. Examples include Peach, Toad and Dr. Mario from the Mario series, and all the characters from the Star Fox and Fire Emblem series.

Originally, the costumes were known as Mystery Suits ; however, the name was dropped in the final version of the game.

Unlike with most of Mario's transformations, Costume Mario's forms typically bear little resemblance to Mario himself. As such, it is unknown whether Mario is donning an elaborate disguise (similar to his other transformations), whether he physically transforms into other characters/objects, or whether the "costume" simply refers to the "character"/"object" being a graphical re-skin of Mario (in keeping with the typical use of the term in gaming). However, the concept of characters disguising themselves to look like flawless duplicates of other, dissimilar characters has been used in Mario games before, such as King Boo disguising himself as Bowser in Luigi's Mansion and a Birdo disguising herself as Peach in Mario and Luigi: Superstar Saga.