Neon tetras are not active per say, and they remain in the lower half of the tank. Rasboras, the species here at least, are very sedate and remain (unless stressed) basically mid-tank. The gourami are mid to upper level, basically surface fish. Need floating plants (and I don't mean duckweed!). Corydoras are active, but not in the same sense as danios and most barbs.
Numbers of a species. Another very misunderstood but crucial factor. Some call tetras, rasboras, danios, barbs, cories, rainbowfish, and a few other groups schooling fish; I prefer shoaling as it does not carry the technical aspects of "schooling" which apply almost (but not totally!) to many marine fishes like herring. Freshwater species that "shoal" are, for me, those that live in large groups, and this is a significant requirement--a group. With most species, you can't really have too many (so far as the number itself is concerned, obviously tank space in even the largest home aquarium will eventually limit numbers)--but you can have too few and the fish are always harmed as a result. Scientific studies have proven that a group of ten of a species will be in better health, and have a significantly better and "easier" life, that will a group of five or six, or three. Aggression is heightened with groups less than ten [some species, such as Tiger Barb for example, need around 15 to avoid real issues]. The fish in these small groups also show a serious latency to feed. They also are more prone to sudden darting at the slightest provocation. These three factors clearly indicate that numbers is a serious issue for the fish.
It all comes back, again, to the genetics of each individual species. The fish "expect" to be in a group, because evolution has programmed this into their DNA, and when they are not, it has negative consequences. At the very least, increased stress. And considering that 90% of all disease in aquarium fish is brought on by stress, this should be a concern of every aquarist. A group of 15 tetras will inevitably be healthier, less stressed, more "normal" in their activities, than will a group of six--all else being equal. There are several other factors that affect fish health too. The green citation in my signature says it all.