When his father goes missing, Smith's character teams up with the Pokémon investigator to find him. Reynolds is used to being a hero.
Starring alongside Reynolds will be Justice Smith, who will be seen in the upcoming Jurassic World: Fallen Kingdom, and Big Little Lies actress Kathryn Newton.
The role is said to be motion capture in nature, sources say.
Considering how Pokémon has sold hundreds of millions of games and billions of trading cards, fans are simultaneously delighted and blown away by the casting choice.
THR is reporting Ryan Reynolds is set to voice Pikachu in Detective Pikachu.
The film will be directed by Rob Letterman, who previously directed the honestly-pretty-good Goosebumps movie.
As of now, Detective Pikachu remains without a release date. Newton is reportedly playing a journalist aiding them along the way.
Ryan Reynolds will play the titular character, Detective Pikachu, who is a pokemon Pikachu that claims to be a great detective.
The movie is based on a 2016 Japanese video game that requires players to solve mysteries with the help of a talking Pikachu dressed like Sherlock Holmes.
He'll play the title character, as The Hollywood reporter first reported. It will also be produced through Universal Pictures, who will distribute the film in the US and most global markets.
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