It seems like once a week we get someone coming either here or to /r/NintendoHelp asking about whether or not they’re allowed to make YouTube videos using Nintendo music or asking how to use Nintendo music and avoid copyright strikes.
[OverClocked ReMix](https://ocremix.org/) is a long-standing site that hosts royalty free remixes of game music that you can use in any project so long as you credit the artists and you aren’t profiting directly off of it (e.g. you aren’t making YouTube videos of just music).
They have lots of remixes of music both old and new, and because it’s original work there’s no chance of getting a copyright takedown from Nintendo or other music rights holders.