Editing SD card

''Ultimate'' saves all snapshots to internal storage by default, after which they can be moved to an SD card. Though replay data cannot be stored on SD cards, they can be converted to video files which are stored on the SD card. Unlike in ''Brawl'', custom stages cannot be put onto an SD card.

SD cards have been an integral tool for applying software modification and running homebrew on Nintendo consoles ever since they were made natively compatible with the Wii, due to the ability for a player to place files from a computer or otherwise downloaded from the internet onto an SD card. These usually involve placing files on the SD card in conjunction with various exploits on their respective console to trick it into running unsigned code and other custom data. ''Brawl'' uniquely features its own such exploit in its [[Stage Builder]], known as [[Smash Stack]], which involves placing a corrupted custom stage file onto an SD card; in addition to allowing for the installation of [https://wiibrew.org/wiki/Homebrew_Channel the Homebrew Channel], this also enables [[file replacement]], as well as gameplay mods such as ''[[Project M]]'' and ''[[Balanced Brawl]]''. This exploit is particularly famous for being more resilient compared to other Wii exploits that were patched out via system updates, as well as working on the Wii mode of the Wii U, as Smash Stack is contained entirely within ''Brawl'' itself. A [https://github.com/yellows8/3ds_smashbroshax homebrew exploit] using ''Smash 3DS'' as well as a custom file on the SD Card also exists though it was patched via [[List of updates (SSB4)/1.1.3 changelog|a game update]]. In Switch consoles released prior to July 2018, by preparing files on an SD card that apply runtime patches to the console's operating system, one can load custom data and apply it to any game, facilitating [[mod]]s and other hack packs.

Besides file replacement, SD cards can be used with homebrew to dump save data, which not only allows for creating backups should something happen to the console, but can also facilitate transferring save data between consoles when it would otherwise be very difficult or impossible. ''Brawl'' save data normally cannot be copied to an SD card since all Wii games with Wi-Fi support disable it (except for unknown reasons, ''{{s|mariowiki|Mario Strikers Charged}}'') both versions of ''Smash 4'' normally disallow any form of save copying aside from transferring data between consoles and the 3DS' ability to convert physical saves to digital, and ''Ultimate'' normally requires a paid Nintendo Switch Online subscription to utilize the cloud saving feature. The ability to dump save data also allows for it to be opened in a save editor, allowing players to edit parameters such as coin count or other battle statistics. Another common application is running cheat codes, such as invincibility hacks, or similar gameplay hacks.