This is a rather obscure crossover, with Dot and the Kangaroo, an Australian cartoon from 1977. It has no category on fanfiction.net or archiveofourown.org, and relatively few works on deviantart.org.
Somehow, I had never known about this fic before now. If you haven't read it yet and don't want to be spoiled, don't bother reading the rest of this post.