More characters confirmed!!
http://andriasang.com/con0sk/project_x_zone_fighters/
God Eater: Alisa & Soma
Resonance of Fate: Leanne & Zephyr
Dead Rising: Frank West
Darkstalkers: Hsien-Ko
Some pics of the magazine scan showing their artwork.
http://www.gonintendo.com/?mode=viewstory&id=176140