Honestly my wifey makes all the costumes and uses what she feels is best (I really just stand there and point at stuff I think looks good and she decides if it’ll work or not, lol).  The only one I can think that is shiny really is Tiana (and maybe Peach), which I think is like a prom dress fabric to make it look more princess like.  Neo Queen Serenity is made to kind of look like a wedding dress, I remember this because it’s super recent so I remember what went into it  :)  Tiana is actually like years old and she’s already pointed out things she’d like to fix whenever there’s time.