Mario is a supporting character of The Annoying Orange. He was expecting to fight Bowser upon entering his castle, but no one was there, so Mario continues forward, attempting to find Princess Peach and Toad, only for Orange to be blocking the way. Mario gets annoyed by Orange, who calls him Spaghetti-O's, even trying to throw fireballs at him, but they fail to cause any harm. Orange burps a koopa shell at him (causing him to shrink), and then he loses a life after getting hit by a Bullet Bill. He later appeared In the Dark, where he killed Mushroom so he could power up. He was on better terms with Orange then. He then left to "get his frog suit", leaving a nearby frog horrified. He has made a few appearances since then. Since season 3, Mario has actually been on good terms with Orange, and has even become an annoying character as well (as shown in Annoying Orange vs. Flappy Bird when he knocks Flappy Bird on the ground and starts hoverboarding with Orange making the same noise as he was). He even appeared in some Annoying Orange Gaming videos.
He is the first multiple show video game character.
Mario being shrunk by a Koopa Shell or shrunk to bite size as said by Orange