Supper Mario Brothさんのイラストまとめ

In Paper Mario, the Group Focus badge is a rarely-used badge that allows Mario's partners to perform the Focus command in battle. This also causes each of them to assume a sprite unique to this badge, depicting them in thought or prayer.

The dragons from Paper Mario: The Thousand-Year Door and Super Paper Mario are supposed to be related to Blarggs from Super Mario World, which can be seen by their original Japanese names. This reference is lost in all other translations.

The files for Super Mario Galaxy contain the body of Ghastly King, the final boss of Donkey Kong Jungle Beat, under the name "BlackMistCreature". While other leftovers from that game exist in Super Mario Galaxy, the name indicates the developers planned to reuse it in some way.

Internal files for Yoshi's Island show that the original concept for Hookbill the Koopa was a Birdo/Koopa hybrid creature. Despite being consistently paired up with Yoshi in Mario spin-off games, Birdo or anything Birdo-related has never appeared in a single Yoshi game.

Prior to the release of Super Mario 3D World + Bowser's Fury, the only 2D depictions of Small Peach and Small Rosalina were pixelated black and white stamps. Now, with stamps being upgraded to color artwork, they have their first official art, shown here extracted from the files.

The files of Mario Kart Arcade GP include this unused smiling Toad model. Its location in the code suggests it was intended to not be merely track decoration, but an interactive object, or even a usable item.

If the player pauses and unpauses the game quickly several times before the Spario microgame in WarioWare: Touched starts, Wario may appear without his arms and mustache. It is impossible to win the microgame in this state (left: regular state, right: unwinnable state).

A highlight of the Art of Super Mario Odyssey book is providing examples of how Nintendo developers brainstorm concepts. One group of Cappy sketches showcases the idea that the brim of a hat looks duck-like evolving into an actual bird design.

A French print ad for Paper Mario, depicting Mario and Bowser battling using scissors. While scissors did not appear in that game, over a decade later, Mario both used scissors and fought against them in Paper Mario: Sticker Star and Paper Mario: The Origami King, respectively.

@Whirlwind_Armor I have prepared a picture of Luigi with his mustache removed for you; I apologize for not including that variation in the original post!