I'd probably do like...one, maybe two of these species. You're probably going to lose at least a few of the rummynoses if you go with them. Having a bunch of male Endlers in the tank chasing down everything in the tank in an attempt to breed is going to stress out your shy galaxy danios. If it were me, I'd do a really big shoal of the neons (if there's nothing else you can cram 20+ in there fine. They'll be happier and they look really cool as a group. Alternately, I'd do a mostly species only group of the galaxy danios with maybe some snails or bottom dwelling fish that aren't going to bother them.