Synopsis:

In the Pokémon universe, Tim Goodman is a 21-year-old insurance salesman who has given up Pokémon training due to the death of his mother and the absence of his father, Harry. He travels to Ryme City – a metropolis where humans and Pokémon live together as equals – to collect Harry's assets following his apparent death in a car crash. In Harry's apartment, Tim encounters a deerstalker-clad Pikachu that can speak and only he can somehow understand; the pair then escape from an attack by a party of Aipom[b] under the influence of an "R"-labeled purple gas that Tim accidentally released upon inspection. They take shelter at a café where Pikachu reveals that he is an amnesiac detective who was Harry's police partner, and that they were investigating a case together when Harry disappeared. They look for Lucy Stevens, a fluff columnist and aspiring reporter suspicious of Harry's death, who Tim had previously encountered. She leads Tim and Pikachu to Ryme Wharf and, after interrogating a Mr. Mime there, are directed to an illegal Pokemon fighting arena owned by Sebastian. He demands a rematch with Pikachu, who previously defeated Sebastian's Charizard. However, after Sebastian gives Charizard a dose of the R gas, Tim attempts to save Pikachu during the rematch. Sebastian then mishandles the R gas and accidentally releases it into the stadium, causing havoc. Sebastian tells Tim that he got the R gas from "the doctor". After confronting police lieutenant Hideo Yoshida about Harry's apparent death and the possibility of his survival, Tim and Pikachu are brought before Ryme City's benefactor Howard Clifford, who reveals to Tim that Harry indeed survived his car crash, which was caused by an attack from a recently escaped Mewtwo, which took him away and left Pikachu with amnesia. Howard warns them of his son, Roger, who he claims is in de facto control of his company and the city. Tim and Pikachu recruit Lucy and her Psyduck on an expedition to the lab facility Harry was investigating, where they learn Sebastian's "doctor" was a researcher aided by Harry, who had been experimenting on Mewtwo, recaptured after escaping 20 years earlier.[c] They are soon attacked by several Greninja who chase them out of the building, but are fended off by Psyduck. They then escape a field of colossal Torterra, but Pikachu is gravely injured. Tim manages to communicate with a Bulbasaur and takes Pikachu to a clearing in the forest where they are greeted by Mewtwo, who heals Pikachu. Mewtwo attempts to reveal its intent, but is captured by Roger. Thinking that he betrayed Harry to a vengeful Mewtwo, Pikachu leaves Tim while the others return to Ryme City to warn Howard. Pikachu comes across the area where Harry's car crash occurred, and finds evidence that the Greninja attacked Harry, not Mewtwo.