Pikachu

A talking but unintelligible Pikachu with an addiction to caffeine and Identity Amnesia, whose only lead on his past is the name and address of a missing detective named Harry Goodman in the deerstalker detective hat on his head.

After realizing Harry's son Tim can understand him, Pikachu convinces Tim to let Pikachu help Tim find his father, and hopefully who he was at the same time.