The new trailer for Dissidia Final Fantasy NT gives a detailed breakdown of how the 3×3 battles will work. Every available character has one of four classes and how you put your team together will affect your performance in the arena. Square Enix has given us a flowchart detailing the new classes:
If this is difficult to follow, the trailer provides all the information that you will need for now. Pre-orders are open now and as with most Square Enix titles, Dissidia Final Fantasy NT does have an Ultimate Collector's Edition.