Keroro

Keroro is the main protagonist in the anime series Sgt. Frog (AKA Keroro Gunso)

Keroro only appears in Plushy Battle Royale 2.

Keroro's rival is Thanos, which some playable characters have that rival.

History
Keroro's the leader and sergeant of the Keroro Platoon. He can be a very goofy guy, but he has some successes to his missions. The Keroro Platoon contains of Tamama, Giroro, Kururu and Dororo. He lives in the Planet Keron. But since he's been found by humans and wants to take care of him, he decides to stay on Earth.

Attacks
Keroro has some attacks more powerful (maybe) to the use of advantages. These includes:

Keroro's Energy Ball: Shoots out balls of energy at the opponent.

Full Armor Transformation: Transforms into the Full Armor Keroro and shoots out plasma beams and hit the opponent.

"Super" Transformation: Transforms into "Super" Keroro, you see him glow and shoots out a powerful blast of fire.

Trivia
He's also in the manga Sgt. Frog.

Keroro and Thanos are from different universes, but rivals against each other.

Keroro's formidable opponent is Starky.