In the Forest of Okoya, Koko is a feral child who has been raised as a Pokémon by the Mythical Pokémon Zarude. Koko has grown up never doubting that he is a Pokémon even though he can't really use any sort of moves. Ash Ketchum and Pikachu meet Koko and help him protect the Great Tree from the crooked scientist Dr. Zed.
| Actor | Role |
|---|---|
 Rica MatsumotoSatoshi (voice) | Satoshi (voice) |
 Ikue OtaniPikachu (voice) | Pikachu (voice) |
 Moka KamishiraishiCoco (voice) | Coco (voice) |
 Megumi HayashibaraMusashi (voice) | Musashi (voice) |
 Shin-ichiro MikiKojiro (voice) | Kojiro (voice) |
 Inuko InuyamaNyarth (voice) | Nyarth (voice) |
 Kantarô NakamuraZarude (voice) | Zarude (voice) |
 Shoko NakagawaKaren (voice) | Karen (voice) |
 Koichi YamaderaProfessor Zed (voice) | Professor Zed (voice) |