Personally I find that fairy types, no matter their color are usually more cutesy style in as far as the art itself goes. This is true of the canon pokedex pokemon too. I haven't seen any fakemon fairy-types though; but my feelings about fakemon in general are mixed.
But I'd say if you want a good start; look at Audino, Dedenne, Pachirisu, Flabebe and Sylveon. All of them are super cute and fit the model for a fairy typing. (Either as an egg group or flat out Fairy combat type). A lot of cases of "Fairy" types in previous gens were of the Fairy Egg Group, as the Combat Type did not exist until recent generations. So you can draw inspiration from previous generations too where Egg Groups were present to classify Fairy-types.
I'd say there's some sort of standard body shape, but I'm not 100% sure what that is; but I'm sure the correlation can be found by observing Fairy typings across generations to see exactly what the pattern is. This I hope might point you in the direction of making a nice looking fakemon that wouldn't look or feel out of place. :3
