of the fish you list, I forsee the texas as being the bully. The rest of those aren't too bad, The Dempsey can be a firey booger but if theyu all started at the same time, in the same tank I don't think there would be too much problems.
As for the oscar, they may grow faster, but it won't grow so fast it will eat the others, plus they aren't really aggressive. They have great personalities but...they are reeeaaly messy eaters, filtration is key when they all get bigger.
Happy fish keeping to you!!!