I had female fighters before. They do ok with eachother as long a you have a lot of hiding spots for them. They need to have I guess you could call them "vision blockers" like plants and ornaments because they will nip at eachother if there is a lot of open swimming room. Mine got along fine just put a bunch of plants and stuff in with them. But I don't know about mixing them wit anything else. They didn't like it when I put in a plecko even. Women I tell ya.....lol
When you say gang up do you mean on each other? or other fish? Strange the guy at the shop said they were very timid and peaceful and may be bullied by things such as male guppies. Anyone found this?