I can't speak for every red-tail puffer out there, but mine have at various times lived with cardinals, whiptail catfish, Limia, halfbeaks and Corydoras. They don't strike me as particularly nippy or aggressive fish, and what aggression there is tends to be among one another. About the only interspecific aggression I've ever seen is where a female red-tail puffer would drive off a bleed heart tetra that got too close. She'd lunge towards the tetra a short distance, and once the tetra had swum away she went right back into her cave. She wasn't trying to bite the tetra's fins, so far as I could tell, and it looked exactly like a cichlid defending its hiding place.
So while I wouldn't recommend mixing them with slow-moving or long-finned fish, like fancy guppies for example, I think they're worth gambling with if kept alongside the usual barbs, loaches, tetras and catfish. Rasboras should be fine too. No idea about blue-eyes -- they are a bit small.
I will observe that I find red-tail puffers more outgoing in big tanks than small. When kept in a 15-20 gallon tank they seem to hide a lot. In the 44 gallon tank they swim about all day, right up to the surface.
Cheers, Neale