Pokemon has been fairly popular in Japan for decades but following the release of the Pokemon GO mobile game, the Nintendo IP (they're part of The Pokemon Company consortium which also featues Game Freak and Creatures) has skyrocketed to unprecedented heights of fandom in the US. As such, Legendary Pictures quickly snapped up the film rights to Pokemon and announced plans for a live-action film based on the Nintendo 3DS game - Great Detective Pikachu.
Yesterday, Variety reported that Nicole Perlman (Thor, Guardians of the Galaxy, Captain Marvel) and Alex Hirsch (Gravity Falls) are teaming up to write the first draft of the screenplay. The project is still without a director or cast but it's expected to begin filming next year so stay tuned for future announcements. At the very least it will be interesting to see how Legendary plans to pull off a live-action film.
For a bit of background info, the Pokemon franchise began on the Gameboy, with its first release in 1996 from developer Game Freak and publisher, Nintendo. Since then, it's gone on to launch an anime series from OLM, Inc. in 1997 that's still ongoing today, amassing a gargantuan 930 episodes and counting. There have also been 18 anime films released with all having a central theme revolving around an encounter with a Legendary Pokémon.