LogFAQs > #880564284

Zero is canonically far superior to Mega Man in every category (by extension of him being on par with X, who was BUILT to be far superior to the original Mega Man). He also has double footwork speed due to Active form.

Also, Zero excels at melee combat. He's much more in his element here than Rock, AND Zero can punch really damn hard: https://www.youtube.com/watch?v=-cKu-ySLK9s&t=5m22s (if X is around 5 feet tall, Zero just punched through like 10 feet of whatever that future warbase is made of)

He also had a fist weapon in Mega Man X8 that lets him do street fighter moves, so he has hand-to-hand skills.