Myth has it that if he defeats you and steals your mask in the dream world, its gone forever in the real one unless Misterioso Grande is defeated. In his debut episode he steals Penny Plutonium's mask resulting in her making a makeshift mask and missing several days of school. Rikochet, The Flea, and Buena Girl go to investigate and discover what happened. Rikochet agrees to enter the dream world to challenge Misterioso Grande for Penny's mask. They collide in an epic battle but Rikochet defeats him and all the masks he stole are returned to those he stole them from and he disappears seemingly never to be seen again. He returns for his revenge in "Field of Screams". where he escapes the dream world and steals nearly everyone at the school of lucha's masks. Rikochet, the Flea, and Buena Girl team up and once again defeat him this time for good.
- Misterioso Grande has immense powers in both worlds, a nod to Freddy Krueger from the Nightmare on Elm Street series.
- Also at the end of the debut episode, Penny's dog wore Misterioso Grande's mask implicating that Penny's dog is Misterioso Grande.
- He was voiced by Carlos Alazraqui, and Dee Bradley Baker.