He is a young eccentric boy who is determined to find his missing father with the help of the other main character Detective Pikachu and convincing Mewtwo to restore his father back to normal.
In the movie, he is portrayed by Justice Smith, who also portrayed Franklin Webb in Jurassic World: Fallen Kingdom.
When Tim was a child after his mother passed away, he was in custody of Grandma Goodman when his father is missing, Already an teenager, he becomes Detective Pikachu's partner to find his missing father Harry and convinces Mewtwo to restore his father to normal.
After being witnessed that Mewtwo is possessed by Howard Clifford, Tim Goodman manages to free Mewtwo from Howard's mind-control by grabbing his mind-possessing device from its head, freeing Mewtwo in the process.
Then Mewtwo then restore everything back to normal and destroy the aggressive formula in the process. Mewtwo then restores Pikachu and Harry back to normal to make peace with Pokémon after Howard Clifford is arrested for kidnapping and manipulating Mewtwo.
Tim Goodman manages to reunite with his father Harry and becomes the next detective just like his father before him.