Here's my 50 cents on the matter, since this aspect wasn't mentioned in the opening post. Belisarius will win because of two things:
A) Technological advantages. Quality of arms and armour have improved considerably, giving them a clear advantage over the troops of Scipio. In fact, feel free to correct me if I am wrong, but weren't the Romans at Scipio's time still largely using bronze?
B) Knowledge. Simple as that. Belisarius, having knowledge of Scipio's accomplishments, is bound to know of what the man was capable of. So whilst Scipio might have some tricks up his sleeve, superior knowledge of the future (from Scipio's perspective) plus countless of experience with invaders and such, will definitely give Belisarius the advantage.
As said before, if any of you find something wrong, feel free to correct.
