>>19933939And to expand on some of them
Evolution methods - neat shit to evolve Pokemon, like the way they retconned Feebas
Your Room - Decorating your room of course
Actual Event Locations - Actually going to an area to catch the Pokemon instead of it being handed to you. And Special events when you bring it certain places.
Post game challenges - bosses like Rivals, Steven, Cynthia, Colress, etc
Rematches - Trainers, Elite 4, Gym Leaders, etc
Breeding Mechanics - I'm not entirely knowledgeable on breeding but I'm pretty sure these have changed over time
Mansion - that rich guys mansion
Backwards compatibility - When Pokemon appeared depending on what you had in the gba slot. Phased out with the 3DS I guess
That's really it, everything else seems self explanatory
