Only do one specimen per species. Females usually transition to male, even if a male is present. Plus sourcing flashers that are truly female and accurately identified can be difficult.I've been looking at adding some flasher wrasses, specifically some Carpenter's Flashers (Paracheilinus carpenteri).
I was thinking about 2-3.
Is it better to get all females ( if you can find them) ?
Or a male and a couple females?
Once you have that species, can you add other flasher wrasse species?
Specimens of different flasher species usually do better together than multiple specimens of the same species.