There's not a lot of endgame in general once you get there.
The way the leveling scaling works in terms of actually doing damage to things makes all the lategame bosses a raw level/stat check, which means you just need to fly around with 500 red balls catching 10 of every shitter pokemon that is under level 25.
It's pretty mindlessly grindy for no particular reason, and even then beating the tower bosses doesn't even do anything - they don't drop any unique items, or their pokemon, and you don't need the tech points from them at all.
We'll see in a few months or whatever what they can end up doing with the endgame, cause everything right up until level 40 or so is an absolute blast.