Throwing a shell towards a wall at the peak of Mario's jump will cause the shell to rebound off the wall and land under his feet. When Mario throws a shell he is not able to interact with it for ? frames. This means he needs to be at least 2 blocks from the wall in order to bounce off the shell.
Frame Window
When Mario throws the shell, there is a 2-3 frame window for it to land underneath Mario's feet.NoteWhen Mario is close to a wall, there is a 3 frame window. While when Mario is further away from a wall there is only a 2 frame window. The timing for shell jumps as Super Mario in the New Super Mario Bros. U game style is 2 frames later than every other style.
Basic Shell Jump
There are two main variations of a standard shell jump, a standing one and a running one. The standing one allows the player to have more control over when to do the jump, while the running run relies of quick thinking.
Shooting a fireball right before Mario bounces off a shell will allow the fireball to kill the shell after Mario lands on it. This trick is only possible as Fire Mario.
Note: See the main page for full variations
This trick requires the player to do a frame-perfect Midair Input in order to bounce off the shell without needing to rebound it off another object.
