How did Ryan Reynolds end up as the voice of Pikachu? It’s possible that only director Rob Letterman (Monsters vs. Aliens, Goosebumps) knows for sure. Letterman is at the helm of Pokémon Detective Pikachu, the first ever live-action Pokémon movie, coming next year from Warner Bros. Twice-Oscar-nominated cinematographer John Mathieson (Gladiator) is the DP, Marc Sanger (Gravity) edits, and Framestore, Image Engine, and MPC are among those contributing VFX.