In Sun and Moon, there is no 'dress' category for the female character, so I assume there are no more dress items. I imagine they decided to do this because dresses would contradict the whole relaxed vibe of Alola's clothing items, consisting of tank tops for the guys and short shorts for the girls (which I don't think were available in Kalos I believe).
That being said, check here in case I missed something. It's a list of every available clothing item in Sun and Moon.
Hope I helped. :)