Here are some off the top of my head, based purely on character similarities. They have nothing to do with priority or power, only the fact that they fill similar roles in their respective worlds:
Guile vs. Heidern-military men on a mission
Ibuki vs. Eiji-ninja wars
Freeman vs. Remy-battle of the bishonen goth boys
Adon vs. Joe-crazy kickboxers
Alex vs. Goro-grapplefest 2K
Cammy vs. Leona-they have their orders-maybe they’ll start kissing
Makoto vs. Kasumi-youthful tradition endures
Dudley vs. Karman-fighting like gentlemen? Yeah, right!
Sakura vs. Shingo-fangirl vs. fanboy
Sean vs. Hokutomaru-when young prodigies collide
Gen vs. Tung Fu Ru-older than dirt!
Yun and Yang vs. the Jin brothers-they could do this one in Capcom vs. style tag team battle
Mike Haggar vs. Griffon Mask-Wrestlemania 2K2, perhaps?
Mike Bison vs. Rick Stroud-not part of the undercard