Quoted By:
ntr, I think I know a way I can make this work in game.
After the 7th gym the game will calculate your favorite pokemon (based off of in game questions, the amount you use it, time spent in amie).
You will wake up and the pokemon will be gone from your party, replaced by a note telling you to go to your rivals house.
The door will we locked, but you can peek into the window. You will be treated to a show of your favorite pokmon and your rival. petting, kissing, nothing to bad, this is a kids game after all Your pokemon will look more happy then ever.