Wrong he didnt beat ruby and emerald. It wasnt 1vs1 against ruby and emerald. He beat them using summon and partner with heal and items like potion and stuff. So plenty of stuff he doesnt have access to.

He mostly rely on teamwork something he cannot get in zelaron melee which is going to be giving him a weakness over X.

X on the other hand is quite the loner in the battle field which give him an advantage already but even bigger when you count what i said above. That Cloud is a mostly team work dependent in most situation.