>>44394851The pocket monster: the animation light novel which was written by Takeshi Shudo (the head writer of the OGseries) explained that both Ash and his grandpa (from his mother's side) left to become Pokemon trainers shortly after Ash was born and Delia first lied to Ash and said they were strong experienced trainers but then admitted the truth that they were both deadbeat trainers when Ash was old enough to easily find out if he looked at the Pokemon League placings and not find either of them there. I think the implication was that they were both too ashamed to return to Pallet Town which Delia resents them for since she was left alone to work at the family restaurant and care for Ash when she herself wanted to be a Pokemon trainer.
