Mario's Quirk was only ever seen under the effects of the Quirk boosting drug Trigger. In this state, it is shown to be a gigantification type Quirk that gives Mario four arms which he can control simultaneously, makes him as tall as buildings, and turns his skin charcoal black.  His physical strength increases by a significant margin due to the drug Trigger, making this Quirk very powerful. He is easily strong enough to pick up a car and swing it around like a toy.
Nothing is known about what the Quirk is like when it is not under the effects of Trigger. It is known that it is not as powerful, however.
- ↑ 1.0 1.1 Vigilante - My Hero Academia: Illegals - Manga: Chapter 2, Pages 26-27
- ↑ Vigilante - My Hero Academia: Illegals - Manga: Chapter 2, Page 40