one of my bettas is in a 29 gallon tank with coris, rams, variety of tetras, danios and white clouds (the white clouds are amazing, they got along in every situation where I had a community with bettas), as are the coris. The danios only worked in my 29 gallon tank I had a few in with a betta in a 2.5 gallon and they fin nipped, most likely due to the smaller space. I moved those same danios into my 29 gallon with my other betta and they now no longer fin nip.
I have another 3 gallon tank with a betta and 1 siamese algae eater. The algae eater likes to try to school with my betta and JD is always like "what the heack dude...personal space here!" lol