Just increase the synchronize's effect of matching the user's nature to 100% and I'll be happy...
I got a long wishlist of suggestions, but probably won't remember most of them for this post.
I'll start with some minor but annoying.
-Make pre-evolution moves relearnable
I'm tired of this dilemma with most stone evolutions... say I have a perfect bred Pokemon, or a decent shiny one. Whether it's a Roselia, Clefairy, Munna etc... they all lose access to most of their learnsets after evolving with a Stone, so I then have 4 moves on them they won't be able to relearn if I delete them, but I don't feel okay deleting a few to make room for more important moves, because I'm not sure if I won't change my mind later....