I like that you can make mons that you used through the story usable in the post game or for online battles thanks to Super Training. I know its easier to just breed for perfect stats but I really apriciate having the option of using mons that I have grown attatched to durring the story for more high level battleing like battle tree or online.
This is a super underapriciated feature and i would be devastated if game freak removed it.