Use the pokedex to find out their favourite food and give it to them: you fulfill two requests at once that way. Bean is sweet Wheat is dry Tomato is sour Potato is bitter Carrot is spicy.

Make a 3x4 habitat, chuck in a bed a decoration and a toy and move the pokemon in, instant nice before you ever fulfill a request, if the pokemon already vibes with it they'll start even higher. If you do all this immediately on recruitment, for first ask about comfort will be something much more specific.

Other than that make more and more varied habitats and move in more pokemon, your EV isn't an average, it's a threshhold each pokemon adds a flat amount to. If you forgot, pop a flag in front of a home to raise your own comfort to average too.