Basi is the largest hippo in his pod. As a hippo, he is massively portly and well-built. He has hairs on his muzzle and notices in his ears. He has dark brownish-gray skin, a pale underbelly, dark spots on his back, and dark rims around his eyes.
Much like his son, Basi is a gentle giant with a sunny disposition. Basi is amicable and open, willing to engage in conversation and negotiate according to the customs of his homeland.
Being so learned in the ways of the animals, Basi is knowledgeable and wise. Despite being an animal with a very different way of life, he understands the customs of the crocodiles and how this affects his pod's everyday life.
Basi is first seen when Beshte brings his friends to Big Springs. While there, Beshte explains to them how the fish pick his hide and teeth clean, and Basi adds that the crocodiles eat the fish when the population spikes, thus fulfilling the Circle of Life.
In the midst of their talk, Pua, the leader of the crocodiles, approaches and asks Basi how the fish are faring. Basi suggests that the float come back next week, and Pua amicably agrees, leading his crocodiles away. However, before he can leave, he is challenged by Makuu, who accuses him of being afraid of Basi. The two arrange a mashindano, which Basi explains as being a physical contest that determines the leader of the crocodiles.
When the mashindano takes place, Basi watches alongside his son, Beshte. At the start of the event, Basi can be seen chanting, and in the midst of the brawl, he comments that Pua is too tired and weak to take on Makuu. Not long after this comment, Makuu wins, and Basi explains that as defeated leader, Pua is banished from the crocodile float.
Basi makes his final appearance when the Circle of Life is brought back into balance, with the crocodiles returning Big Springs to the hippopotamuses. As Makuu strides sullenly out of the water, Basi calls out after him, inviting him to come back once the fish are in plenty. He reminds him that all he has to do is ask, and Makuu promises to keep the proposition in mind.
Along with Mbuni and Twiga, Basi practices a song for the Kupatana celebration. Simba listens from a nearby hillside and warmly compliments Basi's performance to Beshte, who tells the king that Basi has been practicing relentlessly. At the official celebration, Basi contributes his voice to the opening choral piece, and he watches in awe as the baobab blossoms begin to bloom.