What is Scratch's copyright rules????
-aGoldslime

Basically, the idea is that if you use someone else's creations in your Scratch project, you need to properly credit them. You can do this for anything that was made on Scratch. If you use things that were not made on Scratch, it is your responsibility to determine whether you have the right to use them. As far as the Scratch Team is concerned, as long as you provide proper credit, you can use other copyrighted material in your projects.

If another copyright holder sees you use their creations in your content, they can submit a DMCA takedown request if they choose to do so. In this case the Scratch Team will take down your project, but you won't be in any trouble unless you continue to post the same sort of content.