You can mix species of each genus, except probably Pseucocheilinus. For Cirrhilabrus, it is worth paying attention to which complex each species comes from. See wrasseguy:If I get them I like the males better. I don’t like the female coloration at all.
Would the H. Claudia and H. Cosmetus be ok? I like those two I think the most out of the Halichoeres category so far.
The black leopard looks awesome too. I really like the gem tang so anything that’s similar coloration to them I think are cool looking. Kinda why I like the squaretail bristletooth. It has the spots and yellow but it’s brown body instead.
H. nebulosus is pretty too. I like •Paracheilinus mccoskeri, •Pseudocheilinus Ocellatus, •Scott’s fairy, •Cirrhilabrus isosceles, •cirrhilabrus laboutei, •c. rubrisquamis, and •c. aurantidorsalis after looking at fairy/flashers.
In terms of males/females is it one male for all wrasses or one male of each species like halichoeres/cirrhilabeus/etc?
Same goes for other genus like Halichoeres, but there's less information readily available about which wrasse belongs to which complex. I would try to avoid mixing species that look similar in color/pattern and shape.
For the wrasses you list, Scott's fairy is probably not a good idea (see aggression level), and C. isosceles could be picked on by any of the other bigger fairies (laboutei, rubrisquamis, aurantidorsalis), but you could also luck out. I try to stay in the green and yellow zone. I haven't had a mccoskeri yet, but most wrasse people speak favorably of them.