It's the blue gourami that I would be most concerned about regarding aggression, but they are usually okay with other community fish. They can become quite nasty to each other and other kinds of gouramis, however, so don't mix 'n match gouramis at some later stage. Also to minimize aggression try to keep only male or only female livebearers. Males will sometimes harrass the females badly. Be aware that even if you have no males, the females may still give birth as they may come carrying fry even if they don't look pregnant when you get them from the fish store.