1. Bring back the Challenge Mode option (it seems they aren't available this time)
2. Make another dex with families lined up together. For example, Pichu is in front of Pikachu, and Gallade is right next to Gardevoir.
3. Make Poison and Ice useful. I'm sure competitive players would be able to explain this better.
4. Give extra nice items for completing the dex, like the Shiny Charm. Maybe something like a Devon Pass (being able to buy Devon products without paying, like Dive Balls and such)
5. RSE rival evolves their starter to the final stage before quitting as a trainer. This is badly needed. Also, make us battle Wally more than twice throughout the game so we can see how his team changes overtime.