Pegatrix serves as Lia Venegas's primary Guardian Alicorn Bakugan, succeeding Gorthion. She first emerges from a mysterious white flower surrounded by interdimensional goo in a Los Volmos forest clearing following the second Great Collision, instantly bonding with Lia.

A self-styled queen, Pegatrix possesses a strong will and distinct opinions on Lia's conduct. Her dual nature combines formidable battle prowess with a deep appreciation for beauty, sometimes creating friction as Lia challenges her perspectives to strengthen their partnership.

Pegatrix exhibits unique abilities, including calming surrounding creatures—demonstrated when pacifying Wynton, Dan, and Lightning. Her aerial skills make her effective for reconnaissance and locating BakuCores during battles. She participates in key Battle Planet events, aiding Bear's rescue from Strata the Hunter and witnessing the membership contest between Magnus Black and Shun Kazami.

During Geogan Rising, Pegatrix experiences an absence, leading Lia to temporarily partner with Haos Fenneca. She returns in Evolutions when elemental Vestroian energy triggers Bakugan evolutions. This infusion grants Pegatrix new forms, including Titan Pegatrix—her super-evolved state and second true Guardian form for Lia. Her physical game stats reflect this progression: Haos B-Power rises from 300B in Battle Planet to 500B in Armored Alliance, while her Aurelus B-Power remains at 700B in Battle Planet.

Merchandise captures her evolving forms, such as the Neo Pegatrix variant in Evolutions featuring refreshed deco, faction symbols, and Nanogan integration for enhanced battle power.