yyyyyyyyyyyyy Graham is probably a nightmare in dueling class; talented, but holy hell is he volatile, more a berserker than something principled. That said, depending on what you have in mind, Graham and Shifu don't have to have negative CR! In his canon, Graham appreciates anyone who can give him a good fight and deeply respects his superiors if they can give him a solid beat-down.

tl;dr yes CR good. Do you have any particular ideas?