Just looking through a New Horizons wiki real quick, this is what I found: Apollo's house is white, which might fit in with a pastel theme. So is Chief's. Chow himself is pink, and parts of his house are white. Gruff and his house are a kind of pale-ish green. Vladimir is pink, and so is his house.
They might look different in-game, but just looking at the wiki, that's what I saw that might work for you. You might try looking at videos of the game, or even visiting a dream town with the villagers you're considering, to see what they look like in-game and at different times of the day.