So it turns out that the AI for this game isn't very bright sometimes...
I was playing around in Arcade mode on Very Hard and I picked Ammy and just spammed nothing but crouching L and watched what the CPU did to it. My opponent was Iron Man and the only thing he did in response was Unibeam, and it went over Ammy's head because she was crouching and too low for the beam to hit. The thing is though, he kept doing Unibeam over and over again just as long as I was spamming crouching L. I even made it go to a draw without a single hit made in the match.
Another character this works against is Felicia, she doesn't even use a projectile, the only thing she does is spam <- H even though she's not even next to me. It's hilarious. Wolverine walks back and forth and then does a jumping S, rinse and repeat. She-Hulk has to be the biggest ****** out of them all though, all she does is try to do Chariot, but gets hit by crouching L, goes back and does Chariot to get hit yet again, over and over.
MODOK, Thor, and Tron all do their projectiles but they head straight over ammy even when she's doing standing L.
Other characters like Chris and Sent will be confused and walk back and forth and try to hit you with projectiles that leave them wide open such as Flamethrower and Neutralize. Though eventually they'll hit you with one of their other projectiles that does hit you such as Shotgun, Grenade Toss, Sent Force L, ect.
But there are also characters that hit you immediatly and have no problems with it such as Magneto always does his Magnetic Tempist, or Wekser will shoot you with his pistol.
On the weekend I'll make a video of all this.