Super Smash Bros Ultimate 100 Save ((link)) -

Disclaimer: This article is for educational purposes. Modifying your Nintendo Switch violates the Terms of Service of Nintendo. Proceed at your own risk.

To install a downloaded 100% save, you need a homebrewed (hacked) Switch running custom firmware (like Atmosphere). Once hacked, you can use save managers like JKSV or EdiZon to inject the downloaded file. Super Smash Bros Ultimate 100 Save