Right now.. these are probably most of the arguments I can possibly think of right now.
Cloud has the influence of Mako in his blood and is stronger than the average human, especially evident that Cloud can wield such tremendous weapons and can do such feats as use his punctured body as a fulcrum to throw someone. This should help to lessen the advantage that X has, being a machine, but obviously being that Cloud is still in essence human it cannot eliminate the fact that X is still a machine and is stronger in comparison even to the other machines X encounters.
I am not sure as to the immediate usefulness of this but Cloud can do sword catch from Ehrgeiz and could be able to abuse this if X ever tries to whip the Z-saber on Cloud. It is of course highly disputable if Cloud could indeed catch the Z-saber. Cloud can also interrupt combos and since Z-saber hits multiple hits like a combo and weapons like charged buster that leaves plasma can also be seen like a combo Cloud may be able to interrupt these. Both of the aforementioned can be followed with a counter hit which apparently in Ehrgeiz do more damage than direct hits.
The mentioned air dash attacks or any other head on attacks could be countered Ehrgeiz style with throws/grabs or counter attacks.
Cloud can use his "evade" ability from Ehrgeiz.. which allows him to dodge attacks and this ability can be used consecutively to dodge multiple attacks. Evade can also be used in the air and Cloud continues to move while evading (if he is already in motion). Evade will be most effective against most of X's attacks (of which are almost all projectile). An important example is dodging X's charged buster attack.. while X shoots the attack Cloud can run and jump evade in for a close attack. Thus Cloud can prove formidable even without flying.
If in desperation Cloud can use his ability of flight from Kingdom Hearts, which is without saying a great advantage, especially for mobility and for avoiding most of X attacks. However, it should be noted that flight takes a large toll as Cloud must reportedly stop for as much as 5 seconds after flying.
Cloud has some special abilities like meteorain, but unfortunately take time to cast and Cloud would become easy prey for X and X's ability to shoot quickly. Cloud could probably be able to pull these off while flying though. Or he can use the Ehrgeiz versions (he has some shot attacks and metorain) which are faster since its from a fighting game.
Cloud can recover from being knocked down in "stand up" moves from Ehrgeiz which allows him to have limited invincibility or use the "evade" ability or even counter attack after standing up. This should be useful if Cloud is hit.
Cloud's blade the Ultima Weapon should not be underestimated. Ultima Weapon is not just an oversized sword and "isn't even technically metal, it's a weird half-energy, half matter composite if anything." A weapon of such properties would probably be able to deflect concentrated energy in the form of projectiles or at least absorb the impact and could probably match X's Zero saber. The Ultima Weapon is also the most powerful weapon in Kingdom Hearts as well. Clouds blade could also prove useful as a shield for blocking and deflecting attacks.. especially the projectile attacks along with the "evade" ability. Cloud's blade is additionally a far reaching and damaging weapon.
Senesia has brought out a very strong and annoying (for argument against X) point of the invincibility for X after sustaining damage. This allows X to be invincible for some time after he has been hit and is used as a powerful point by Senesia that any attacks that involve multiple hits or combo attacks will be useless since the first hit will activate the invincibility. For now, unless combo attacks can be treated as a single attack, only the first hit will be effective thus rendering many of Cloud's attacks ineffective.. especially those from Ehrgeiz and attacks like omnislash. For this the ability to "tackle" from Ehrgeiz will prove useful as an opponent who is invincible can be tackled. Cloud can use one hit specials or multiple hit specials that end quickly and follow with a tackle move.
There is a limit to how many times the maverick weapons of X can be used (limits are around 18 24 36.. not much of a limit.. and then the W-tank). And then there is U-Buster which allows all shots to be charged shots. But charged maverick shots must finish before maverick weapons or charged shots can be used again (is this different in X6? or have i remembered incorrectly?).
This should give Cloud a small opportunity. Added also that Cloud would probably be able to sustain damage from more than one charged shot, the Ultima Weapon should be able to protect Cloud somewhat, and Cloud may be able to dodge some of the attacks especially with evade; Cloud could use one of his stand up abilities after being hit and may be able to survive until X uses up the energy. Also to note is that none of those maverick weapons are specifically Cloud's weakness and maverick weapons do not do a whole lot of damage to bosses that are not weak to the specific weapons. This may improve Cloud's ability to resist damage from those weapons.
Also to note is the mention that Cloud can stomach a
supernova: (merriam-webster) the explosion of a very large star in which the star may reach a maximum intrinsic luminosity one billion times that of the sun. I would say thats a whole lot of damage to stomach and if that is weak.. then perhaps you should scale up all attacks in ff7 as I'm pretty sure most of the attacks in megaman x series are not to the degree of exploding stars.. not to mention things of "magical" power.
Or maybe Cloud can taunt X to death (Ehrgeiz) and piss X off so much that his circuits burn out.
Anyways, I tried. lmao
ehrgeiz -> mame ~27mb zip ;i like fighting games
megaman zero 1/2 -> gba ~3.5mb ;small & may have details to end this.. and who doesnt like megaman?
have a version of x5 but it doesnt run (freezes comp with black screen probably comp fault)
ill probably never get my hands on x6.. sounds cool/fun tho