Accessed via the Options menu, a Name must be selected or created, to allow customization to begin - thereafter, the new control setting will apply to games played with that name only. Prior to Super Smash Bros. Ultimate, it is not possible to globally alter controller settings.
Once a name is selected, any of the four basic control schemes - Wii Remote, Wii Remote+Nunchuk, GameCube controller and the Classic Controller can be edited. In Super Smash Bros. for Wii U, this number expands to seven, with the Wii U GamePad, Wii U Pro Controller, and Nintendo 3DS also being supported. For Ultimate, four control styles are supported, those being a single Joy Con, two Joy Cons, Nintendo Switch Pro Controller and GameCube controller. If, for instance, the player wishes to change the Y button on their GameCube controller to shield rather than jump, they must select the GameCube controller, then select the Y button and set it to "shield".
The "standard" actions - attack, special, jump, grab, and shield - can be set to any of the available buttons. Smash attacks and taunts can also be configured, but they are only available for certain buttons. The functionality of the left control stick and Start-Pause buttons can not be changed.
Since Super Smash Bros. for Nintendo 3DS does not support Name Entry or alternate controllers, only one configuration can be saved for each copy of the game. In contrast to the console versions, controls can only be swapped between the buttons instead of selected from a list. The ability to alter smash attacks and taunts is also not provided.
If the control scheme that is edited is the same type of controller used during the edit, then the START/PAUSE or + button can be used to bring up a test area where Mario can be controlled on a completely flat stage to test out new controls. Once the control editing is complete, the controls can be saved to the custom name that is selected. Then, whenever that name is selected in a match, the controls will follow the customised settings.
Custom controls are used to perform many different techniques that would be more difficult or impossible to do otherwise. For example, B-sticking is required to perform Lucas's Wavebounce and his Magnet Pull.
Custom controls are fully legal in tournaments, and players are allowed to redefine controls to any degrees; before a tournament set starts proper, players are also allowed to test their custom controls before in a brief match before the start of the set, in what is known as a "button check".
Super Smash Bros. Brawl Controller Settings
Super Smash Bros. for Wii U Controller Settings
Super Smash Bros. for Nintendo 3DS Controller Settings
Super Smash Bros. Ultimate Controller Settings