>>34342773Make it a fully fledged sequel to Sun/Moon. Increase the game length significantly. Bring back gyms, the Pokemon World Tournament and Battle Frontier.
Make it challenging for long-time players, and make sure that towards the end of the game, you're facing trainers with a full team of Pokemon.
Besides that, they could have expanded areas, the golf course, etc. They could have added more things to do, more challenges, more rewards, more exploration, etc, etc.
Basically; Just make the game worth the $40.