Essentially, this game scrapped the post game and put the Magnagates in its place. It's a real bummer for people like me who prefers the post game to the main game in PMD games, but on the flip side, there's now technically "infinite" dungeons.
The usual stuff applies though, yeah, but instead of 8 Level 1 dungeons, we're now given 2 and forced to buy 2 of the others. You can also work on completing your "Pokedex;" ie, recruiting all the recruitable mons which, again, should go by pretty quickly due to there being significantly fewer than previous titles, and having increased recruitment rates.