Gouramis tend to be peaceful towards other species. Not so much with their own. Males especially will fight except for dwarf croakers(AKA sparkling gouramis) and chocolates with chocolates being iffy. Most dwarfs in the pet trade are male, the females are considerably duller. In 40 years I've never seen a female at a chain store. Multiple gouramis in a smaller(30 gallon and under) tanks is not the way to go for a peaceful community. 1 anabantoid(gouramis, bettas, or paradise fish) per tank unless they're females, dwarf croakers or chocolates.
EDIT: I have seen male pearl gouramis get along as adults, but even then it was in a 55 gallon.