In the publishing world, editors often talk about wanting a book that is "unique, but familiar." So they're looking for books that are different from anything the world has ever seen before. And at the same time, they don't want books that are too unusual.
It sounds like a riddle that can't be solved. But here's how Snowcap Mountain Adventures solves it. I often describe this series as Thomas and Friends meets skiing. It's unique because it's set at a ski area. And it's familiar because it's a lot like the Thomas series, which everyone already knows.
So my advice is, if you want to sell publishers on your idea, describe it as a bit of a mash-up!