Underground Bases of DPPt. I didnt rack up 1000+ hours doing nothing.
Me and my mate used to make mazes for each other to get through in our bases
Edit: I also miss end game content =P XY seemed really lacking in that regard unless you were playing competitive PvP. Seems ORAS has this fixed though, so many legendaries to go catch (hopefully with some story to it) and the Delta Episode.