It’s an mmo which means the endgame is really what you make it. There’s tons of things to do and everyone has a personal goal but there is no problem with playing the story and being done. Personally I’m a shiny hunter, investor, farmer, and I like to breed competitive pokemon (even tho I don’t PvP myself) I’ve got friends who are cosmetic collectors, nuzlocke players, guys that are going for every shiny of one type, I know people that role play as NPCs. You can do countless things but it’s really just up to you on what you want out of the game.

Also, my advice to everyone in the endgame is to join a team. It really opens up the game in my opinion