pokemon

First a world that's larger and more connected but not open world (open world is a meme that needs to die). Something like Monster Hunter Stories 2 (MHS2) 's connected map.

Have Pokémono use actions to interact with the overworld depending on their level and moveset, such as flying, swimming, digging, or say using vines to latch to a tree the other side of a chasm to cross over. So something like MHS2's overworld actions.

Have an engine that allows for a decent combat flow with turns or something like ATB, with better indicators for actions and statuses, and with a proper HUD to log turn events. So something like MHS2's battle engine.

Have a plot that, like, at least pretends your character is pivotal somehow for the adventure rather than playing a spot that any nobody can fill. So something like MHS2's plot.

Drop the attempt at hi-fi / realistic rendering of Pokémon and instead turn to models that are simple, kinda toy-ish and easily recognizable by focusing on what makes each Pokémon distinctive. Not to mention more varied efficient so you can actually have a Pokémon with claws use those claws and be watchable at above 15 fps. So something like MHS2's models.

Overall, basically just do MHS2 but with Pokémon. There's a reason my official statement before PLA came out was that MHS2 was the best Pokémon game for the Switch (play as a Trainer, collect and train 6 mons, deal with elemental powers and stuff, complete a champion challenge, etc).