We've had the same formula for two decades with little to no innovation.

For example what's stopping developers from using say:

-The breath of the wild engine for the open world
-Climbing, bike, boat mechanics
-Having simple customized mc's
-taking control of the pokemon you send out.
-each pokemon has stats denoting movement speed, damage and type, defence ect.
-pokemon can run, fly, dig, teleport with a stamina bar
-attacks mapped to the face buttons and can be held down for a secondary effect.
-An online hub zone for battles and trading.
(Or even better a dark souls like pvp based off of highest level in party)

And that's literally it.
Hell they could even cheap it out and port the models from the handheld games to the switch and add movement animations.

What's stopping the japs /vp/? Why can't we get the game we've wanted since we were kids?