The on-screen touch controls use the N64 controller button icons from SmashWiki (ssbwiki.com), created by Toomai Glittershine.
License: Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0). The files are unmodified. Any modified version of them is also CC BY-SA 4.0.
Per-file source URLs: web/icons/n64/ATTRIBUTION.md in the repository.