Hippopotas is a quadruped, hippo-like Pokémon that is most commonly found in deserts and other arid places. Its skin color depends on gender: if male, it is tan with dark brown patches, and if female, its coloring is reversed. It has a large snout with round nostrils and eyes that protrude from the top of its head. It torso has mottled coloring and a small hole on its back. Each of its feet has two blunt claws, and it has a small tail. Hippopotas spends its time bathing in sand and avoids water at all costs. It covers itself in sand as a protective measure against germs and expels sand instead of sweat. When it walks through the sand, it shuts its nostrils. It prefers to travel in groups of ten.
Despite having obvious gender differences, both Hippopotas and its evolution have only one menu sprite and one Dream World picture, both of which depict the male variation.
Hippopotas is based on a hippopotamus, with army-like camouflage. Because of the spout upon its back that spits sand, Hippopotas and its evolution may be based upon the legendary Bahamut as, in some accounts of the myths behind it, it is said to support a bed of sand and have the head of a hippo.