Capcom decided to make some easy money, so they recycled parts of Mega Man X5, threw in overly difficult trial-and-error gameplay, made almost everything an obstacle course, and called it Mega Man X6.
Rolanmen1 completes all stages as X and Zero using the same controller inputs across both. This goes to show that the two characters do in fact play similarly. It should be noted that a patch is needed to be able to play as Zero from the beginning; this is normally not allowed. Please refer to the rules for more details.
An alternate encode featuring an input display and audio commentary by the author is available right here.