I've got emperor and Congo tetras and cories with my angel; far too big for him to ever eat and they never bother him.
In fact the emperor tetra I've had in all sorts of tank with loads of different tank mates since I've had them and they have never, even once, been a problem with anything; if you want a large-ish, peaceful shoaler, they come highly recommended by me; I've had the Congo only a couple of weeks, so I can't say for sure they're as phlegmatic as the emps.