In my opinion, an 80 gallon tank is a very small for 1 oscar, or 1 Jag.
It is probably OK for 1 adult Texas, or OK for 1 adult GT .
If you put juvies of the above, in an 80, it will work for a while, as long as you plan for much larger tanks in the future.
Why you ask?
All the fish you mention above are somewhat, to very territorial, and an 80 gallon tank is smaller than any 1 would claim as its territory.
Another reason is water quality, each as an a adult all put out tons of waste, and even with the best filtration available, the water will become urine soup in less than a week. The smaller the tank, the more water changes you are going to need to do.
Lets say you change 50% of the water once per week.
It would be like putting a great dane in a bathroom, 24/7, and cleaning out 50 % of its feces once per week.