Ultimasaurus is a large Tyrannosaurus-like Pokémon. It has a hybridized appearance of many different Saurian Pokémon; it has the head and body of a Magmasaurus rex, the frill and horns of a Terratops, the arms and legs of a Kyodachus, the back armor and club of an Ankylomite, and the plates and spine-tipped tail of a Stegomizer.