As stated before, this Marill is very similar to the recurring Jigglypuff as it loves to sing for an audience and gets furious when its audience falls asleep on it. The only difference between Marill and Jigglypuff is that Jigglypuff scribbles on the audience, whereas Marill uses Tail Whip on the audience.
Hippopotas made his first appearance 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.
Hippopotas's second and final appearance was in Sleight of Sand! with his father, Hippowdon. In this episode, Butch and Cassidy also wanted to kidnap the Hippo Pokémon, but they failed.
Personality and characteristics
Hippopotas is a happy-go-lucky Pokémon that enjoys being close to his herd of family and friends. He wags his tail when excited. Hippopotas was initially anxious and even bit down on Ash's hand when they first met in Mass Hip-Po-Sis. After he was rescued from a precarious situation and offered some food, Hippopotas became incredibly friendly towards Ash and his friends. He has a healthy appetite and can swallow a large apple whole. In Sleight of Sand, Hippopotas instantly recognized the group and happily greeted them.