"Mushroom Battle mode is one of the highlights exclusive to Tekken Tag Tournament 2 Wii U Edition. This adds Mario themed items like Super Mushrooms that make fighters grow, Poison Mushrooms that shrink and damage characters, and Super Stars that grant temporary invincibility. I played Mushroom Battle mode and it has more of a "party game" kind of feel than standard Tekken.
Producer Katsuhiro Harada explained while you typically get stronger when you eat a mushroom, growing changes the distance and range of your attacks.", writes Siliconera.