I'm actually a huge Street Fighter fan that plays SSFIV daily, so it makes me happy seeing this thread ^_^
Anyway, if I could do a Street Fighter move in real life...honestly it'd have to be a Hadoken. I don't think it'd get much better being able to shoot plasma from your hands. But if that's too boring of an answer, I guess I'll go with Cammy's Cannon Spike. Be able to go vertically with a thrust kick only to land on your feet. That'd be sweet.
I'd say Akuma's Shin Goku Satsu (Wrath of the Raging Demon). Time pauses, everything turns black, four kanji characters meaning "die a thousand deaths" appears, then you inflict a punishment to your opponent that no word can describe.