What if battles 2

Android 17 and Android 18 vs X and Zero

Z-Buster

Z-Saber

Dark Hold

Twin Dream

Rekkoha

Durga Glaive

V-Hanger

Bashou Fan

Titan Breaker

Kaiser Knuckle

Absolute Zero

Sachi: As well as another trademark technique, his ground punches, each with various effects, from fiery explosions and balls of electricity...

Megumi: To waves of energy and BEAMS OF LIGHT! But don't think his Z-Saber gives him no means of ranged attack.

Toomi: His saber can fire off... a fireball, as well as a homing missile, bladed wheels, a wave of energy that travels across the ground, and the homing crescent Denharei. But Zero does have access to one alternate form: Absolute Zero. Zero cannot hold this form for long, but with it, he gains an increase in close-range attack, increased mobility and the ability of flight with his wings, and a deadly pair of claws.

Megumi: X has stopped Sigma's plans upward of 10 times, and is traditionally the one who ultimately defeats Sigma.

Toomi: He's also defeated the former S-A hunter Vile, the Soul Eraser Berkana, the double agent... Double, as well as the Zero Nightmare, a copy of Zero made by the Reploid scientist Gate.

Sachi: And Zero has managed to save his friend X on multiple occasions, one-shotted a doppelganger of himself, and has defeated the Soul Eraser Gareth

Feats

X stopped Sigma's plans 10 times

X is often the one who defeats Sigma

X defeated Repliforce and Rebellion Army with Zero and others

X defeated Vile, Berkana, Double, Nightmare Zero, and Gate

X founded Neo Arcadia

X ethereal form mentored an amnesiac Zero in the MMZ series

X outruns city swallowing blackholes on daily basis (Gravity Beetle fight and Intro)

X can shoot Blackholes or become the epicentre of one himself (Squeeze Bomb X8)

X can regen to full from nothing but his unmanipulatable soul (MMX3 Manga)

X defeated Infinity Majinion (a being who could multiply to infinite copies of himself)

X defeated Lumine who could create and collapse a pocket dimension big enough to hold a sun in it.

X can absorb enough energy capable of destroying entire Japan with just his buster and not even full body.

X replicate defeated foes abilities plus use stronger versions of it.

X defeated Zero in X2 and drawed a battle against Zero in X5 while Zero had an extra Saber and peak of his potential while X was in his strongest Armor but neither had a Saber nor peak of his abilities.

X became stronger than Zero. (MMX6 Zero Ending "There is a superior hunter")

X can always seem to come back in some form eventually even without a body.

X fought a 100 year war alone against countless Mavericks and won it.

X's body is the only thing capable of being strong enough to be used as a seal against Mother Elf