Koko is a human boy who serves as the protagonist of Pokémon the Movie: Secrets of the Jungle. Originally named Al Molybdenum, he was found as an infant by a lone Zarude after his biological parents, Chrom and Phossa Molybdenum, were killed. The Zarude adopted him, named him Koko, and raised him in the Forest of Okoya, leaving the Zarude troop to care for the child. Koko grew up believing he was a Pokémon, communicating fluently with the jungle Pokémon and considering the Zarude his father, whom he calls Dada. He is energetic, curious, and deeply loyal, but he also feels frustration at being unable to use Pokémon moves like his adoptive parent.

Koko's central motivation is to protect the forest and his father, while also seeking to understand where he truly belongs. His role in the story involves meeting Ash Ketchum and Pikachu, who help him realise that he is human. This revelation forces him to confront his identity and the truth about his parents. He struggles with feeling caught between two worlds, but ultimately embraces his dual nature as both human and Pokémon. His key relationships include his deep bond with Dada, his friendship with Ash and Pikachu, his complicated interactions with the other Zarude, and his conflict with Dr. Zed, who caused his parents' death and now threatens the jungle.

Throughout the film, Koko develops from a feral child unaware of human society into someone who understands both cultures and decides to become a bridge between them. In a crucial moment, he demonstrates the ability to use a version of the Zarude move Jungle Healing, channeling the energy of the forest to heal his injured father. This ability, combined with his knowledge of Pokémon language and his agility, sets him apart from ordinary humans. Ultimately, Koko chooses to leave the forest to explore the human world, carrying the memory of his parents and the love of his Zarude father, while maintaining his role as a guardian of the jungle's secrets.