Jecht being Cosmos was confirmed ages ago actually, same with Terra being Chaos. It's Tidus and Cloud's alignment's that threw most people off. As they both appear to be Chaos side despite having no foreshadowing like Terra and Jecht did.

Prishe is an Elvaan from FFXI: Chains of Promethia. She plays a rather large role in the expansion and is a Monk/White Mage. She was also originally considered to be the main representative for XI for the first Dissidia but was passed over for Shantatto.