Nine Williams is a great hand to hand fighter and I’d probably say that she may be better than Chun Li in that department. She was overpowering Ken and even held her own against Ryu for a second. That being said, Nina has no fancy super powers or energy kicks and that will hurt her. Energy attacks can deal massive damage and I see Nina being taken out for the count as soon as one of those blows land. It will mean Game Over. Chun Li wins.
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Chun Li has fancy super power and energy kicks but she lacks grabs and wrestling warfare, she might hurt Nina but would be helpless as soon as Nina manage to make a grab on her. Then Nina would just have to perform a serie of chain-throws to defeat, break and kill her.
Nina getting up close to do that to Chun Li is were I see the plan falling apart though. Chun Li is still skilled enough to keep proper spacing the whole time and that’s when Nina will be going down for the count