From what I understand, the original Undertale and its characters obviously have copyright, but what about its AUs? I was planning to use some characters from certain AUs in my Roblox game. But I’m not sure if I can, or if they’re still restricted.
A lot of Undertale games pretty much have AU’s in them so it’s fine to add them. I haven’t recall Toby Fox forcing people to take down games if they use his stuff. Besides, you can simply credit him.