local, regional, national and global tournments.
the champions can make its own gyms: build the puzzles, choose the pokemon, the AI, the quotes, and the visual of the gym leader(and elite four and champion).
So, after beating the game, you can enter in the local tournment, and the champions choose the leaders. Being a local leader, you can enter the regional, if you win, you can be a regional leader(leaving yout local post to other), this repeat for national and global leaders.
If you dont want to compete in this online tournment, you play the game as usual. But after beating the game, the leaders will be upgraded to local leaders, and you can defy them again and and local elite four and becamo the local champion(in your game). Than, the leaders will be updated to regional, than, national, than global.
So, it would be a very long post gaming chalenge.
And if you update every month with a new tornment, the game would be infinity.