Some of my Pokemon have started having flavour text during battle such as Dozing off, and this is due to Affection gained through Pokemon Camp.
However there are a lot of things that can happen within Pokemon Camp: playing with toys, chatting to one (or multiple) Pokemon, sending Pokemon to play with one another, and then there's the whole cooking curry section with multiple different ingredients and berries.
So all of that begs the question: what is the quickest way to raise Affection?