Casting and Production

The film was officially announced in July 2016, although Legendary Pictures were reported to be in talks as early as April of that year. The Pokémon Company and Letterman wanted to adapt Detective Pikachu because of their interest in making a film that focused on another character besides Ash Ketchum, the protagonist of the Pokémon animated TV series. Rob Letterman was hired to direct the film on 30 November 2016, and the studio's fast-tracked production start in 2017. After a few negotiations by Legendary to write the screenplay, Hernandez, Samit, Letterman, and Connolly received screenplay credit, and with Hernandez, Samit and Perlman received "story by" billing.

In November 2017, Justice Smith was cast in the lead human role, with Kathryn Newton added to co-star after an intense session of reading and testing actresses opposite Smith. Despite a fan petition to get Danny DeVito to voice the yellow protagonist, Ryan Reynolds was cast in the title role, portrayed via motion-capture and voice-over, in December 2017. In January 2018, with production commencing, Ken Watanabe, Bill Nighy, and Chris Geere joined the cast. In February 2018, Suki Waterhouse and Rita Ora were additionally, with Omar Chaparro joining in April.

Principal production began on 15 January 2018, in London, England, and Denver, Colorado. Nine days later, Legendary announced that principal photography had officially begun. Much of the onset interaction and vocal reference for Pikachu was filled in by Jon Bailey. However, all of his dialogues were dubbed over by Ryan Reynolds. Principal photography concluded on 1 May 2018.