There are many people recently either confused or just don’t care, but artists can not sell or claim anything that has episode characters in it or trace any work from other artists. I’ll try to explain the best I can! You can, by all means, use reference pictures, but you cannot have the reference picture be a layer of your work, that is called tracing.
If you are caught tracing or plain out just stealing someone’s work and get caught you might be called out by the artist who made the actual piece. But that’s the least that can happen the worst is that you could be sued for a lot of money.
If you see art that looks like it was traced, try reverse searching the image before making a big deal. Because you never know! Please tag people to get this message across!