In Seiyuu terms, Kuja is being voiced in Japan by Akira Ishida. Akira’s the same guy who voiced Makenshi in Final Fantasy Unlimited, with Kuja marked as Ishida’s 3rd Square character. Akira is currently voicing Bae of the Sentai series Gekiranger(next year’s Power Rangers series), and voiced many infamous characters (funny to serious to freaky) such as Gaara (Naruto) and Zexion (Kingdom Hearts series).
Zidane is voiced by Junko Takeuchi, famous for her “Breeches” roles as Takuya (Digimon Frontier) and currently Naruto Uzamaki, marking 2nd time she and Akira are put together in opposing roles (the 1st first being Naruto and Gaara).
I am expecting these US voice actors to voice the two FF9 figures when the game comes here. Though of Crispin Freeman for Kuja, but found a more fitting guy to voice him.
Zidane: Greg Cipes (Beastboy, Teen Titans)
Kuja: Brian Beacock (Yumichika Ayasegawa, Bleach)
Here’s hoping that Dissidia is not just characters from the FF games. Seeing Kaze & Makenshi involved would be cool move on Nomura’s part (Secret Characters?).