Grubba is a blue Clubba that wears a black and green vest with a black hat. He also wears shades, has orange hair, and his shell is purple.
Grubba is first seen hosting a match between Rawk Hawk and The Koopinator. Rawk Hawk wins the match and Grubba awards Rawk Hawk with the Champ's Belt. Sooner or later, Mario enters his room and is happy to see another new challenger. He dubs Mario "The Great Gonzales" and sends him to the minor league room. After some time later, Grubba realizes that Mario is searching for the Crystal Star and sends a threatening mail to him. Grubba even suspects his assistant Jolene may be plotting against him as well. After Mario finds his blueprints in his drawer, he makes for the ring where he reveals that he sucked up all of the energy from the other fighters to keep himself younger and stronger. Using the Crystal Star, he then transforms into Macho Grubba and fights Mario. Mario defeats him and, after turning back to normal, Grubba reveals that he was also responsible for the disappearance of the last champ of the Glitz Pit: Prince Mush. However, Prince Mush suddenly emerges from the machine and Grubba is left there on the ground. It is unknown what became of Grubba after those events.