During his days as a wrestler, he was one of the most recognizable fighters in the Earth Rumble tournaments, due to his extremely large size and unique way of communicating. When he spoke, he left out determiners and articles, turning "Hippo mad!" into his catchphrase. Like The Boulder, The Hippo only referred to himself in the third person.
Team Avatar first saw The Big Bad Hippo in action during the first round of the sixth edition of the popular Earth Rumble tournaments, where he faced off against The Boulder. The Hippo displayed his unique fighting style by catching the rock that The Boulder threw at him between his teeth, chewing it up, and spitting it out, before commencing his signature move, called "rocking the boat". This move proved to be highly effective, causing The Boulder to stagger backward and almost fall out of the ring. At the last moment, however, The Boulder managed to regain his footing and hurl a large slab of earth at The Hippo. The latter possessed enormous physical strength, as he was able to withstand the direct hit seemingly unharmed. Nevertheless, The Boulder managed to defeat The Hippo by lifting him and the earth he stood on and throwing it out of the ring.
After Aang had won the tournament by easily knocking Toph out of the ring with his airbending, Xin Fu was convinced that the two had cheated and set out to recollect his prize money. The Hippo and the other wrestlers supported him in this endeavor. When the group managed to corner Aang and Toph, The Hippo threw a metal cage over each of them, successfully securing them.
After Toph's parents had paid the ransom to free their daughter, Sokka and Katara wanted to free Aang as well, but were thwarted in this attempt by the band of wrestlers. The Hippo proceeded to lift Aang's metal cage onto his shoulder in order to leave the arena and collect the bounty from the Fire Nation for capturing the Avatar. However, Toph challenged him and the other fighters, promising to beat them all again in an earthbending battle if they refused to release Aang. Engaging in a battle with all the wrestlers at once, Toph succeeded in taking every one of them out. The Boulder, The Hippo, and the Headhunter were the last fighters remaining. The Hippo defended himself by swinging around a large, earthen model of the Earth Kingdom's national emblem. Tag teaming with the other two, The Hippo charged the blind earthbending girl. However, by shifting the earth they all stood on, Toph was able to defeat them easily.
Months later, The Hippo and The Boulder were part of the group of friends and allies who were recruited by Sokka to participate in the Invasion of the Fire Nation. Although once opponents in the ring, The Hippo hugged Toph before the battle started, expressing his joy at being reunited with the "Blind Bandit". During the invasion, The Hippo and The Boulder proved to be very powerful earthbenders as they took down a battlement together, and another along with Toph. In the end, however, the invasion turned out to be a failure and The Hippo, along with the other adults of the invasion force, was captured by Fire Nation forces and sent to prison.
The Big Bad Hippo's fighting style was unique; he enjoyed tossing handfuls of rocks into his mouth, chewing them up, and spitting them at his opponents. His signature move was called "rocking the boat", where he would shift his enormous mass from side to side, literally rocking the ring and knocking his opponent off balance. Aside from his bending, he was also shown to be quite sturdy, easily shrugging off the impact of being struck by large slabs of rock.