Sewaddle first apperead while Ash and ‘Co were in Yaguruma Forest and attacked Pikachu. After Ash tries to catch it and fail, Sewaddle run away but later reapperead and knocked Ash when the trío met Arti, who revealed that Sewaddle was accompanying him through the forest although it is not his pokemon.
Despite showing antipathy to Ash early, Sewaddle started to change his mind when Ash jumps in front an attack of two Woobats to protect both Pikachu and Sewaddle and mainly after Ash jumps to a climb to save it. Sewaddle finally allows Ash to throw a pokeball to catch it and becomes becomes part of his team.
