The X button refers to the grey, cashew-shaped button on the right side of the GameCube controller, the top button of the Classic Controller Nintendo 3DS, Wii U GamePad, and Wii U Pro Controller the small button on the right side of the Classic controller, Wii U Pro Controller, Wii U GamePad, and Nintendo 3DS (varies in colour on 3DS, matches the colour of the Classic Controller, Wii U GamePad and Wii U Pro Controller), and the top dark gray on both the Nintendo Switch's Joy-Con and Pro Controller. It is used for jumping while fighting. In Super Smash Bros. Melee, Brawl, and Smash 4, it also changes the palette swap on the character selection screen. The Nintendo 64 controller, Wii Remote, and Nunchuk do not have a X button. It also appears on the Wii U GamePad and Nintendo 3DS for both installations of Super Smash Bros. 4. When using Joy-Con (R) as a single Joy-Con held horizontally, the X button will become the right button, acting like an A button and performing standard attacks.
Gallery
The X button on a Joy-Con and Pro Controller
| Controllers and buttons | |
|---|---|
| Nintendo 64 controller |         
|
| GameCube controller |           
|
| Wii Remote (and Nunchuk) |           
|
| Classic Controller | L R        
|
| Nintendo 3DS |            
|
| Wii U GamePad / Pro Controller | L R            
|
| Joy-Con |                
|
| Switch Pro Controller | L R 
|
| Third-party controllers | Hori Mini Pad · Arcade controller · Keyboard |
| Other | Smash Controller · Controller modification |