Pokemon: Detective Pikachu director Rob Letterman immediately knew Ryan Reynolds would be the “perfect” person to voice the character.

In the upcoming movie, based on the 2016 video game Detective Pikachu from the Pokemon franchise, the Hollywood actor has been cast as the voice and facial motion capture of the main figure – a world-class detective and exceptionally smart Pikachu whom only Tim Goodman (Justice Smith) can understand.

While Ryan may have been an unexpected choice for the role, Rob is adamant that he has the ideal voice.

“For some reason, Ryan’s voice just popped from the very start,” he said in an interview for Total Film magazine. “You want a big personality in a small adorable body, and that was just the perfect fit.”

Pokemon: Detective Pikachu also features Kathryn Newton as a reporter and Ken Watanabe as Detective Yoshida, a veteran Ryme City police lieutenant. In addition, Bill Nighy, Suki Waterhouse, Rita Ora, and Rob Delaney have been cast in undisclosed roles, and while it is great to have landed so much star power, Rob was mostly concerned with capturing the Pokemon world accurately.

“There’s so much pressure to make sure we get this right, for everyone. We had a lot of conversations with the experts, making sure it’s properly authentic in terms of the rules of the universe, but my whole thing was that I just wanted everything to feel real,” the filmmaker shared.

Previously, Rob has made movies like 2015’s Goosebumps and 2010’s Gulliver's Travels. And while he was always intrigued by the concept of making a Pokemon film, it was his two children who convinced him to sign on for the project.

“I missed that whole craze growing up, but my kids are huge fans,” he smiled. “When I got the call asking if I was interested, my kids were actually in the room at the time and they started jumping up and down screaming, ‘You gotta do it! You gotta do it!’ So, I kind of didn’t have much choice!”