I think it's similar to adding a note to a book, and then removing that note, leaving you with a the original book. That scenario doesn't violate copyright law as far as I'm aware.
That's not how patching a rom works. You directly replace data and the formats that let you undo have to put a copy of the original data in the patch file. So yes it is a risk.
I recently stumbled upon https://www.hackdex.app/ which is a lovely website dedicated to Pokémon ROM hacks.
It's a really vibrant scene, with a lot of different hacks that go all the way to fully-fledged games, but because it's so rich it can be a pain to find what is available and what the latest version of a given ROM hack is.
This website has a neat feature where you upload any base Pokémon ROM file, and it filters all available ROM hacks that are compatible with it via a neat UI. And of course it offers you a one-click download (well, in-local-storage-patch) to the given ROM hack.
Quick clarification: I'm pretty sure there's no uploading at all; it uses local storage for the filtering too, which is important because uploading a ROM tends to be risky legally
Is this in any way related to byuu, the SNES emulator author?
I imagine. What motivated using that combination?
It's a really vibrant scene, with a lot of different hacks that go all the way to fully-fledged games, but because it's so rich it can be a pain to find what is available and what the latest version of a given ROM hack is.
This website has a neat feature where you upload any base Pokémon ROM file, and it filters all available ROM hacks that are compatible with it via a neat UI. And of course it offers you a one-click download (well, in-local-storage-patch) to the given ROM hack.
Source code: https://github.com/Hackdex-App/hackdex-website