It also allows for creative play, the open world allows you to get gym badges and HMs in any order. Since all pokemon are catchable, there are many pokemon added to wild encounter locations. There are other cool features that I will share as I play.
There are some new items available, move tutors added and moveset changes made to improve playability. Making player sprites sounds cool though. It is pretty interesting but I have no idea how to use it.
You can inject your own starters and your own character sprites from one of Shockslayer's sites.