You’ll need the base Super Smash Bros. Ultimate NSP. This is the full game from a cartridge or eShop dump.
An is the standard file format used for digital software on the Nintendo Switch. Unlike XCI files (which are dumps of physical cartridges), NSPs are the digital equivalent of what you would download from the eShop. super smash bros ultimate switch nsp update dlc verified
For those using homebrew tools or managing digital backups, follow these steps to ensure your files are verified and working: You’ll need the base Super Smash Bros