Very easy fight for Vanessa who totally dominates Reese. Many things are clearly in her favor: She is younger than Reese, from what I read she is a fanatic gymrat (what we can clearly see from her fantastic body, Reese, although very beautiful, looks very soft compared to her), fitness plays a major role in her life, she seriously learned martial arts for her role in sucker punch (
https://www.youtube.com/watch?v=_up-8U-f0RU): in this various sucker punch behind the scenes we could really see some great moves from her (to be honest, all these girls showed some moves which actually made me feel quite intimidated, even Jamie chung and Emily Brown, and of course Abbie Cornish..wow). She is clearly underestimated, mainly due to her not being quite short. But despite her being just 5'0". She is 5'0" full of energy and seems to be a real bunch of power that can even beat up many actresses that are way taller than her.
Reese on the other hand, despite being a great actress ( I loved particularly in teh Johnny Cash movie) does not seem very fit and also does not seem to have much fight spirit. I think this will be a very one sided fight leaving Reese seriously beaten up with tears in her eyes..