Are you looking to set up for local play?
To install a 100% save file for Super Smash Bros. Ultimate (SSBU) on the Yuzu emulator, you must locate the specific user save directory and replace the existing data with the downloaded files. This process unlocks all 74 base game fighters and potentially additional DLC content if included in the save Installation Steps super smash bros ultimate 100 save file yuzu
That being said, I can provide a detailed review of the concept of a "Super Smash Bros. Ultimate 100 save file" in the context of emulation and the Yuzu emulator. Are you looking to set up for local play