Project X Zone has a huge selection of heroes hailing from Namco Bandai, Sega, and Capcom games. Monolith Soft probably wanted to balance things out for the bad guys so they picked a couple of crossover villains like Vile from Mega Man X.
Vile from Mega Man X
Selvaria Bles from Valkyria Chronicles 3
Ciseaux from Sakura Wars
Lord Raptor from Darkstalkers
Hmm… two from Sega and two from Capcom, but none from Namco Bandai yet? I wonder who will make it into Project X Zone. Tales of Vesperia’s chief villain, perhaps? Monolith Soft also created three original rival characters for Project X Zone.