Mushroom Mario

Mushroom Mario is an unnamed original transformation that appears in chapter 8 of Super Mario-kun volume 5.

Mario, Luigi and Yoshi are tossed in a pipe to the underground, where Mario finds a field of Mushrooms and eats one of them, turning into an anthropomorphic little striped Mushroom. A pack of Monty Moles reach them and yells at the intruders that those are modified mushrooms meant as a trap for Mario (which they later realize it worked). Having stubby limbs, Mario is unable to hit the enemies so, Luigi uses him as a bowling ball, hurting the Moles, that turn into Monty Mole Swoopers and attempt to suck Mario's abilities, but instead they only suck the Mushroom form, becoming anthropomorphic Mushrooms themselves and turning Mario back to his original form.

In Super Mario RPG: Legend of the Seven Stars, one of the curses turns Mario and his partners into Mushrooms, making them skip turns.