It depends on the species of plec, as well as gourami. You may see some aggression between the gourami & angel, as they look similar so one will think it is another gourami or angel. If the plec is a common it will soon outgrow that tank if it's the one in your profile.
Those loachs like to be in groups, I would get a few more. The featherfin may outgrow the tank as well, provided it is the one in your profile., which sounds like a 29 gallon to me. This depends more on the footprint of the tank than anything else. If the footprint is 30x18 that means it is 12" deep, too shallow for angels. If the footprint is 30x12 you have the depth for angels, but are limited in bottom space for the featherfin as well as plec.
Many tetras will get nippy if kept in smaller groups, and they like longer flowing fins for the most part. I would get a few more tetras & loachs, and plan on getting a larger tank if you want to try adding angels to the mix.