When you roll cancel in this game it’s from the first 3 frames of a roll. When you see a actual roll that is next to you, you can throw them the hell out of it… this is easy to do when you’re turtling. If they’ve roll cancelled something, you don’t get a roll animation, just the invincibility string. And if they didn’t roll close enough for you to throw them, you can still c.mp into hp hundred hand slap (yes this combos if you know how to do it right) at the end when they still have vulnerable frames before they can attack. If you really want to know how all the rolling works, read Chensor’s full guide to all this stuff. Point being, if you can see the roll animation, you can throw them out of it.
BTW, roll cancelled super combo doesn’t take on the invincibility properties of the roll either if that’s what you were trying to get at. It stops the invincibility string that the game was still keeping track of (why the specials RC’ed maintain invincibility).
And I don’t care who you play with, if somebody jump in… and gets hit… and jumps in… and gets hit… etc, and never adapts trying to NOT get hit, which would mean NOT jumping in, then they’re friggin stupid because any old scrub who an ground-touching AAA move could beat them. The way for them around this jumping in is a just defense or more effectively, a parry… but in such a case you wouldn’t be nailing them then, huh?
AND, if by super you meant Iori roll cancelling his fireball (a special), then here’s the other part. The invincibility follows a seperate string in the game than the move which you are performing. The invincibility in that move lasts just as long as the invincibility from the roll would. It should be over by the time you hit him. And if he is still invincible by the time your headbutt reaches him… you just sail right through, not just sitting next to him for a free shot.