The Mystery Mushroom, in its current state, can grant Costume Mario one among a hundred different appearances in Super Mario Maker. These costumes, unlocked gradually through the 100 Mario Challenge or if you have the compatible Amiibo figurine, are all based off of familiar in-game enemies and obstacles, or even other famous Nintendo heroes, villains, and guest stars — including the likes of Link from The Legend of Zelda, Isabelle from Animal Crossing, and even SEGA's own Sonic the Hedgehog.
Famitsu previously announced that their mascot, Nicky, will be available as a costume at a later date, and it turns out that yet another costume appears to be on the horizon, this time by way of CoroCoro Comic. The monthly manga publication has recently revealed that a costume based off of Super Mario-kun will be coming soon.
In serialization since 1991 and authored by Yukio Sawada, Super Mario-kun is an official manga adaptation based off of Nintendo's flagship franchise. While its demographic leans more towards the younger crowd, Sawada's manga series retells events and scenarios from nearly every different branch of the Mario franchise. Super Mario-kun has only been published in Japan until recently, with its first international release being in France as of December last year.
With an upcoming update, Super Mario-kun will cross over into Super Mario Maker as a new costume via the Mystery Mushroom, with Mario's own appearance changing into that of the manga. Although no date is given for when the costume will be available, Sawada has noted that he will have a course of his own ready on November 6.
There has yet to be word from Nintendo's American and European branches as to whether this costume, or the Famitsu mascot and Arino of GameCenter CX costumes, will be available in the West.