Galaxius Rex appears in Season 2 episode of Galaxius Rex. He is a Sonorosian who had overgrown into size of its planet. He was exile and was persuaded by Ghostfreak to eat up earth. Gladly, Stranger made him vomit all the planets he ate. He later appears as a cameo in Movie: Battle for Ultratrix eating Pyros.
He have superstrength as he ate up tons of planets! He will digest all the planets in 2000 million years. Like a normal Sonorosian, he can shoot loud sound waves. The Soundwaves are too powerful for almost anyone to survive. He doesn't do that much often because he hates breaking up his "lunch"
As a eater, if he vomits all the planets, he will be as a size of a normal Sonorosian. He'll no longer have strength.
He is a pitch black Sonorosian called Umbrasonorais who live underground in oceans of sound. He grows when he starts to eat up rocks later mountains.