Angles like tons of room. They also like deep water (aka tall tank), especially if they have huge flowing fins. Years ago I had an angle in a 10 gallon, which she outgrew quickly and was moved to a 40 gal.
You need at least a 20 gallon for an angel, and that will still not allow for it to fully grow.
I would stick to just platies and cories. Smaller tanks, like 10 gallons, do best with a max of 2 species, IMO. They look niceer with larger groups of each fish type.