Tifa — a sleeveless crop top t-shirt and shorts with suspenders. (Not a very feminine outfit except for the fact that it shows off her shape, something that would be equally feminine on a woman and masculine on a man.)
Rinoa — a long sleeveless jacket over a short sleeved shirt and shorts. (While Rinoa herself is quite feminine looking, there's nothing in particular about her outfit that is.)
Dagger — pants that continue up into part of a top (not the right part to be called "overalls" but that's the closest to a real world equivalent I can think of), worn over a long sleeved puffy shirt. (It's unusual enough for either gender that I can't think how it would be placed as either masculine or feminine, which probably means it could work equally well for either.)
I don't see anything about any of them that would suggest they should be gender specific. So yes, they can all be put in as unisex outfits, just as their Squall, Cloud and Zidane counterparts are. (I'd kind of like the Rinoa one, though I don't personally care much for the other two.)
Then again, there's nothing about Lightning's or Snow's outfits that justifies a gender lock, either. (In fact, Lightning's outfit was a uniform worn by both genders in the game she came from. It's just that she was the only one with that uniform to be central to the plot.) Yet, for some reason, they did get gender locked. :(
