Here are the rules.
1. Both are teleported to the Disney earth (so no one has the home field advantage.)
2. Aang can't reach the Avatar state and Ben has the original omnitrix (not the ultramatrix.)
3. Aang has mastered all of the elements including lightning and Ben can turn into any of the aliens he has previouly used and the omnitrix can not power out.
4. Both have 20 minutes of prep time to research there oponets on wikepidia.