i wouldn't mix angels with gouramies. both types of fish have very strong personalities and if they decide not to like each other things could go downhill quickly. not saying it's not possible, just have another tank ready in case they feel like hating each other.
I keep my angel with a pearl gourami and they are always by each others side. I also have black neons, no issues. I used to have 3 male rosy barbs, no nipping, i Picked up 4, the females nip, the males don't. :[ Guess It depends on the fish.