List of Super Mario Maker for Nintendo 3DS pre-release and unused content
From the Super Mario Wiki
This is a list of pre-release and unused content for the game Super Mario Maker for Nintendo 3DS.
When Mario obtains a Mystery Mushroom, he gains the characteristics of Super Mario (ducking, breaking Brick Blocks, and spawning Fire Flowers when approaching a status-dependent power-up) while retaining the appearance of Small Mario. When Mario is hurt in this form, a Super Mushroom will fly off of him, just as a costume will fly off of Mario in Super Mario Maker when he is hurt while in Costume form.
Similarly, while the Big Mushroom power-up is unobtainable through normal means, it remains in the game's code and can be acquired through cheat codes. When it is used, Mario appears as Big Mario with classic colors and has all the functionality of Big Mario.
Unused costume data
Although the costumes cannot be used in this version, the files CharaMarioTable.byaml and Boss_CharaMarioTable.byaml (separate table used for costumes from updates and Event Courses) exists in the game's files. The costumes in the game's Boss_CharaMarioTable.byaml file are left unused.