I think everyone looks good, it just depends on the shade. I would say red, but I feel weird about putting Ariel and Rapunzel in red, but maybe purple look good on them all too.

However we don't see Tiana and Snow in the color.

Well, i'm just imagining. But I don't think Poca could pull of pink or purple. White is a color that ayone can look beautiful in if they have the right clothes.

Also blue, maybe green.

or blue :)