Spider-man: Spider sense [Super armor++ He completely dodges the first hit. However when he dodges he’s in a 3 frame stun and moves backwards and his invincibility frames last for 5 frames and the cool down before spider sense can work again is 7 frames after his 5 iframes. So… if you jab him with a 7 frame jab he moves back out of some characters range but isn’t able to retaliate cause he’s at disadvantage. But, if they set up with a projectile or cancel with a dash and attack again they can hit him. Basically it would make him like the comics where rarely does anyone get the jump on spider-man and they usually only hit him cause they gave a set up that’s unavoidable]
Healing factor: Wolverine and Deadpool will recover health faster than other when not in play and at a very slow rate when in play [about 1/3 the rate a normal character heals while out of play, but only red health].
Vibranium adamantium alloy: Caps shield prevents chip damage unless they have super strength, which dishes out more chip damage
Super Strength: Hulk, Thanos, Ironman, Spider-man, and basically everyone who has super strength as a power dishes out more chip damage than normal and can also chip Captain america when he blocks.
energy force field: Ironman and other characters can nullify energy based attacks when blocking and take no chip, like in MvC2 with ironman, iceman, and war machine. But physical attacks still chip and they do MORE chip than normal.
Sigma Virus: adds a poison effect to Tech based fighters like X, Ironman, etc. that either weakens their attack or does damage over time.
Lack of faith: Fighters like Ironman, X, and most tech based fighters of scientific minds don’t believe in magic and thus magic based attacks deal less damage to them.
Non stick coat: Iron man and others have a non stick coating that makes things like Web ball not hold them down as long