Pichu Big is the older sibling of the two Pichu Brothers, recognizable by a small tuft of hair on his head, distinguishing him from his slightly smaller brother, Pichu Little. He calls Big Town home and leads the Pichu Posse, a group of young Pokémon including Magby, Teddiursa, Wooper, and Smoochum. His leadership involves initiating the group's actions and coordinating their responses to challenges.

Personality-wise, Pichu Big displays greater maturity and responsibility than his younger brother. He demonstrates decisiveness guiding the Posse, such as leading their investigation into mysterious crescent-shaped invitations during Meowth's party preparations. A strong sense of fairness surfaces when he insists on returning a found invitation to its rightful owner, Oddish, despite Pichu Little's initial reluctance. His protective nature is clear when spearheading the search for Pichu Little after the younger brother becomes lost during an argument. Though the brothers occasionally clash, Pichu Big consistently prioritizes reconciliation and teamwork, strengthening their sibling bond and co-leadership of the Posse.

His adventures within Big Town include *Pichu Bros. in Party Panic*, where he devises solutions to retrieve the Posse's lost invitations, like orchestrating the creation of a Magby-powered hot air balloon. Earlier, in the short *Pikachu & Pichu*, he and his brother collaborate with Ash's Pikachu to rebuild their clubhouse damaged during a chase with Houndour. Other experiences involve assisting Meowth with chaotic tasks like pizza delivery and gardening, resolving a picnic basket mix-up, and helping locate a lost Azurill. These consistently highlight his role initiating group efforts and mediating conflicts.

Pichu Big's abilities include using the move Thunder Shock. His problem-solving skills are evident in practical solutions like the balloon retrieval plan in *Party Panic* and collaborative efforts to overcome obstacles during their escapades.