Brawlzeus is the buddy monster of Banjoe Onizuka, originating from Danger World and belonging to the Godpunk attribute with a distinct yankee or delinquent aesthetic. His personality is enthusiastic and boisterous, marked by unwavering loyalty to Banjoe, whom he consistently addresses as "bro"; this relationship forms the core of his character.

He is intrinsically linked to Banjoe's development. After Banjoe loses a Buddyfight to Masato Rikuo and promises to cease physical fights, redirecting his competitive spirit solely into Buddyfighting, Brawlzeus actively supports this shift. He shares Banjoe's dedication to the game and their mutual aspiration to become the strongest Buddyfighters. Their partnership features prominently in dedicated episodes exploring their dynamic, including a fiery duel against Yuga Mikado.

In combat, Brawlzeus uses a Danger World deck focused on the Godpunk attribute, employing a strategic playstyle centered on resource disruption—plundering the opponent's gauge and field through card effects and associated costs. His abilities include "Plunder", activating upon attack to deplete the opponent's gauge while replenishing his own, and "Double Attack". An additional effect triggers at the end of the turn if the opponent's gauge is sufficiently depleted, forcing a card from their field into the drop zone.