Pegatrix is a winged equine Bakugan with a unicorn-like horn, described as a pegasus-unicorn hybrid or alicorn. She debuts in the reboot series Bakugan Battle Planet and continues to appear in later seasons, including Armored Alliance, Geogan Rising, Evolutions, and Legends. In the anime, the Haos attribute version of Pegatrix becomes the partner Bakugan of Lia Venegas, a member of the main brawling team, after Lia's earlier Bakugan Gorthion. With the exception of Geogan Rising, during which Lia temporarily uses the Bakugan Fenneca instead, Pegatrix remains Lia's primary partner for most of the series.

Pegatrix has a proud and regal disposition, and official descriptions characterize her as a self-styled queen of Bakugan with firm opinions about how her human partner should behave. She is strong-willed and powerful in battle, but she also enjoys finding beauty in the world around her. Her relationship with Lia is built on contrast and growth. Lia challenges Pegatrix's expectations of her, while Pegatrix pushes Lia in her own way, and their partnership develops around broadening each other's perspectives. A central part of their dynamic is Lia's goal of redefining what girl power means so that the two can become true partners, which gives Pegatrix an arc of learning to appreciate her brawler's independence rather than simply expecting conformity.

Within the story, Pegatrix serves as one of the main Bakugan of the heroic team and participates in battles against rival brawlers, antagonistic organizations, and greater threats over the course of the series. She fights alongside Lia in key confrontations and gains strength through evolution, transforming into more powerful forms such as Hyper Pegatrix and later Maximus Pegatrix. In Armored Alliance, she also uses Baku-Gear equipment such as the Lightning Striker, and fusion variants appear, including a Pyrus version equipped with the Crystal Blaster and an Aurelus version with the Golden Haos Lasers. A Ventus attribute version of Pegatrix also appears in the story, controlled by a doppelganger version of Lia, serving as a dark mirror of the original character.

Pegatrix's notable abilities are tied to the Haos attribute of light and her considerable combat strength. She is described as dominant and forceful in battle, and her abilities in the physical game revolve around manipulating G-Power, such as halving an opponent's power while boosting her own. Her evolutions and equipment upgrades reflect her continued growth as a fighter, allowing her to keep pace with progressively stronger opponents and to remain a dependable force for Lia and the rest of the team throughout the series.