You know, Im gonna venture out on the left limb and say he loses at Ryu, because I think the symbiote would actually interfere with the Dark Hado. I think the Symbiote just agments someones natural abilites, like their strength, or if they have been in chemical accidents, their senses. But Akuma power comes from training, and from evil. Its kind of like a symbiote on its own, so the Dark Hadou would interfere with the Symbiote, trying to vei for control over the body. There isnt anything written down that says it works like that, but we probably wont know unless it actually happens.