The Silly Theory About Ash's Dad In Pokémon Brian Ashcraft Nov 14, 2018, 1:30pm 1 It’s been called Pokémon’s greatest mystery. Where is Ash’s father? There is one theory that Professor Oak is Ash’s dad. If you think that’s bonkers, then this theory is even more out there. What if Mr. Mime is really Mr. Ketchum? Silly, I know!