-Both must be from recent games of their timeline Ryo(King of Fighters Regulation A-2007-), Ryu(Street Fighter 3 3rd Strike-1999-)
-If Ryu needs Dark Hado he can use it, Ryo can use the Tengu Mask
-You cannot use non-cannon/dream match games feats Ex: Vs, Neogeo, Street Fighter Ex, etc...
-You can use cannon feats Ex: Art of Fighting, Street Fighter, Street Fighter Alpha, King of Fighters, etc...
-Morals are off
-Feats or gamplay or story, no glitches or bugs