I've got 3 dempseys with 2 firemouths, a green terror, and a gibbicepps pleco for the last year and with the exception of an occasional fight between the male dempseys they all do fine together
They should be fine. I can't tell you how many fish get along if given enough room. non of those are extremely aggressive so they won't really go for the death of another fish with plenty of place for each to retreat.