>>31311071As for Leagues, remove Ritchie, have Ash lose in the Kanto League to Gary to set up Ash beating him in the Johto League better(In fact, actually have Ash and Gary battle more often in Kanto). Use Jimmy and Silver in the Johto League, with battles against one another, with the winner facing off against Ash before he has to lose. Brendan and Ash battle in Hoenn with Ash winning. Ash vs Paul remains, and this time, Ash loses to either Jimmy or Brendan to show that they're improving too, showing that even those he beats can beat him too, and making him want to train even harder. Unova would go differently. As for Kalos, have him win, but lose to the first Elite Four to show that he still has a long way to go and just winning a League alone won't be enough.
Meanwhile, for the females in the groups, May, Dawn and Marina(Shes had cameos showing she is a Coordinator after Johto) still do contests, and Serena could start after the Kalos arc. Have ocasional episodes showing them and what they're up to after parting ways with Ash.
Basically overall, use more game elements, but it doesn't have to be a complete 1:1 game translation.