@buster cannon, which was why Zero was a more popular and used character in TVC.
Here’s what i think would make Megaman X unique
His gameplay should revolve around his armors. Meaning to say, is making his armors the main meat of his gameplay. A regular form X will only have armor switching as supers (including that huge robot he uses in that KOS-MOS video), no beam/super fireball supers, just armor switching. Armors don’t have any timelimit, just meter costs and each Armor has it’s own move sets, supers, and level 3’s.
Some armors will give him crazy projectiles, while others would make him slow as fuck/immobile but with great vitality/armor and close range damage (like that huge Robot in the KOS MOS video), while one Armor makes him quick and good in rushdowns, yet has shit vitality.
As an assist, his assist changes depending on the armor he has. For example, a Normal X’s shot assist would be his buster, if i go into Falcon armor and tag him out, that assist will be a different projectile. This is cool IMO and not broken, because it will create a very unique strategy play. Some armors will make your shot assist really good, but there are other armors that will turn your shot assist into a crappy assist (yet have a good direct assist).
In terms of busters: X’s buster should be a special and not one of his fierces like in the past MVC’s. Maybe a qcf+p that can be charged (like Ryu’s invincible fireball), and can be unleashed in any direction ( vertical, horizontal, or diagonal) . To balance that and add the diversity between Zero’s buster, capcom should either make X Immobile during the charge, or the fireball doesn’t go full screen.
Edit: i think he can have a buster as part of his fierces, but make them small as hell. He can run with it like a machine gun, but it doesn’t combo or anything. It goes into normal sized when QCF’ed and then stronger with a QCF + P (hold)
X would be a character that requires allot of strategy and memory, making him a more complicated character than Zero and above all UNIQUE. There hasn’t been a fighting game character that is based on transforming. But this can work with EXE and Starforce too.