You already have neons on the original post so, yes they will work. Just be sure you keep the tetras in a school with a bare minimum of 6, 8 or more is really the best size school. The dwarf grourami should work too. I have one with a school of glowlight tetras, ghost shrimp and a bristlenose pleco. He is pretty calm unless a fish comes in his territory, but he has never caused any damage.
That is a lot of fish and livebearers have a high bio-load. What size tank are you putting these fish in out of curiosity?