Affection, Fullness, and Enjoyment are the three stats that Pokemon Amie uses. You can see what your Pokemon’s levels for each of these are when you tap “Switch”.
The ways to boost affection in Pokemon Amie are as follows:
- Petting the Pokemon increases affection and decreases enjoyment. Petting them in areas they like makes the process more efficient.
- Feeding the Pokemon PokePuffs increases affection and fullness. Fancy, Deluxe, Supreme Seasonal, Supreme Wish, and Honor PokePuffs increase affection even more. Once they are too full they will refuse to eat them.
According to Bulbapedia:
When a Pokémon is petted or fed a Poké Puff, a number of hearts will float above the Pokémon. The number of hearts corresponds to the number of points that are added to their affection. In the case of petting a Pokémon that has low enjoyment, a music note is shown instead, since no affection is gained by that action.
When the music note appears, that means they’re bored and won’t gain any affection from petting them. At this point they might also be full. To reset these stats, you need to play minigames. Minigames raise enjoyment and lowers fullness so you can restart the process again.
Other actions that increase enjoyment, but don’t affect fullness, are:
- Talk to your Pokemon
- High-five your Pokemon
- Open “Play” mode
- Open a minigame
This video summarizes everything pretty well