Hippopotas is a quadrupedal, hippopotamus-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 mottled dark brown patches, and if female, its coloring is reversed. It has a large snout with round, protruding nostrils, and several blunt teeth inside its mouth. Its eyes and small ears protrude from the top of its head. It has 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 but keeps its mouth open, swallowing any sand and prey along the way. It removes excess sand in its body from its nostrils, which it also does when angered or excited. Hippopotas is more active during the day, and burrows into sand during the night to avoid the cold. It prefers to travel in groups of ten. Despite its large and heavy appearance, it may remain undetected, due to how well it hides in the sand.
Hippopotas debuted in Mass Hip-Po-Sis!, where Ash, with the aid of his friends, rescued the Pokémon from being trapped upon a high ledge. Rhonda and her Sinnoh Now crew revealed that they were on assignment filming a herd of Hippo Pokémon. It was then discovered that Hippopotas was lost, having been separated from his herd. As a result, Ash and his friends helped Hippopotas find his way back. Like a few other Pokémon, Hippopotas seemed to like riding atop of Ash's head.
Team Rocket attempted to steal Hippopotas multiple times for Giovanni, but their plans were foiled each time. All the while, Jessie had trouble saying the Pokémon's species name. Hippopotas fell into a stream after one of Team Rocket's attempts to capture him. With the assistance of Nurse Joy, Ash and his friends fetched a sackful of dry sand to help Hippopotas recover. Later, the group were able to reunite Hippopotas with his herd.
Pokémon Super Mystery Dungeon: A male Hippopotas is a resident of Serene Village, and speaks with a French accent. After the player brings their partner back at the Epilogue, Hippopotas can be recruited.
This Pokémon was unavailable prior to Generation IV.
Hippopotas seems to be based on a hippopotamus, although its behavior is the inverse of that of the real life species: hippopotamuses are more active during nighttime and often submerge themselves in water, while Hippopotas is more active during the day and hates getting wet. The pattern on Hippopotas's skin resembles desert military camouflage.
Because of the spout upon its back that spits sand, Hippopotas and its evolved form may be based upon the legendary Bahamut; in some accounts of the myths behind it, it is said to support a bed of sand and have the head of a hippo.