Boota

Boota (ブータ) is Simon's pet pig-mole.

Pig Mole Boota
For the majority of the series, Boota sticks around Simon and does very little. His main role is comic relief, but he appears in almost every one of Simon's fights. Once, Boota saved Simon and Kamina by willingly removing his rear end (which later grew back) as food for Kamina and Simon, revealing they can't pilot when hungry. He also tries to comfort Simon in moments of distress, but even his best efforts couldn't snap Simon out of his depression over Kamina's death.

Later on, Boota helps Yoko overcome her memories of Kamina when she pilots Gurren in Rossiu's place. He accompanies the young sniper when she is injured within the Dai-Gunten, but finds himself helpless when the Shuzack enters the scene. Nonetheless, Yoko claimed that Boota was around to protect her, earning a big lick from the pigmole.

When the Super Galaxy Dai-Gurren is trapped in the Sea of Despair, Boota aids Simon and Viral by generating Spiral power of his own to bolster the ship's defenses. After the Anti-Spirals are defeated, he becomes Simon's lone companion during his journey across the earth.

Evolved Boota
While in the Space-Time Labyrinth, Boota assumed a human form due to his spiral power throughout the course of the series. He is the unknown source that the Anti-Spiral detected which prevented their immediate destruction. While in this state, he was able to defeat the fake Anti-Spiral in one hit. Since he was now intelligent, he realized he was trapped in the labyrinth like everyone else and that this form was caused by him being in the Labyrinth. Just as with the others abandoning their fantasies, Boota returned to pig-mole form when he escaped the labyrinth and teleported aboard Tengen Toppa Gurren Lagann with his friends.

Powers and Abilities
Increased Spiral Power: Unlike other members of Team Gurren, Boota has the ability to unleash massive amounts of Spiral Power. He was able to use it to change into a Human form, even though it wasn't real.

Trivia

 * In Episode 2, it's revealed that Boota apparently wears glasses (which greatly resemble his black eyes).
 * Boota, like Leeron, also does not appear to age, being seen with Simon during both the 7 and 20 year time advancements with no notable change in appearance. This is strange considering that much larger, older pig-moles are seen in the first episode, and when Rossiu is loading the Arc-Gurren, implying that they grow with age. However, Boota doesn't grow. It is attributed to the fact that Boota turned his growth energy into spiral power. This allowed him to evolve and use spiral power, but prevents him from growing.
 * Boota (in human form) is possibly Simon's right hand man in the prologue or the series as the two characters share a striking resemblance.