Boota

In his natural state Boota is a small Pigmole, compact enough to perch on Simon's shoulder, with black eyes that Episode 2 jokingly reveals to be a pair of glasses. He never grows; across time jumps of seven and then twenty years his body stays identical, even though other Pigmoles clearly get larger with age. The explanation offered is that he converted his personal growth energy into the energy of evolution itself.

Inside the Multiverse Labyrinth he takes on a second shape, a humanoid Pigmole born of absorbing Lordgenome's Spiral Energy on top of his own vast reserves. Gaining intelligence traps him in the Labyrinth like everyone else, and he reverts to animal form upon escaping to Tengen Toppa Gurren Lagann. His evolved figure closely resembles the unnamed right-hand man beside Simon in the series' prologue, suggesting the two are one and the same.

Loyalty is the whole of Boota. He shadows Simon through nearly every fight, offering comfort whenever his owner falters, though even his best efforts cannot pull Simon out of the depression that follows Kamina's death. His devotion turns physical when the moment demands it; he once tore off his own hindquarters to feed a starving Simon and Kamina mid-battle, since neither could pilot while hungry. He extends the same care to others, helping Yoko push past her memories of Kamina when she takes Gurren's controls in Rossiu's place, and staying beside her when she lies injured inside the Dai-Gunten, helpless against the Shuzack but present enough that Yoko credits him as her protector. Once the war ends, he becomes Simon's sole companion on his wanderings across the Earth.

Boota's defining gift is Spiral Power. He first awakens it in the Sea of Despair, standing in for an exhausted Simon to keep the Super Galaxy Dai-Gurren's defenses alive, then feeding his energy in alongside Simon's once his friend recovers. The novelization goes further, stating that Gurren Lagann ran stronger on Boota's power than it ever had on Simon's, briefly making the little Pigmole the mightiest Spiral being alive. By the final battle he, like every member of Team Dai-Gurren, holds limitless Spiral Power and channels it to amplify his body, enough to brawl with the Antispiral hand to hand.

His other feats round out the picture. He projects his energy in every direction as a protective field, intercepting a shot the Antispiral aims at Lordgenome aboard the Super Galaxy Gurren Lagann; he then absorbs the Spiral Power Lordgenome releases and claims it as his own, triggering his humanoid transformation. He perceives, and can even touch, the otherwise invisible Antispiral, and in his evolved state destroys the entity's body with one strike before it reassembles itself. His regeneration is equally proven, from regrowing his sacrificed hindquarters to sharing in the consciousness-based restoration granted to Tengen Toppa Gurren Lagann's crew.