Crossovers are the staple of just about every fandom there is. Different fandoms have different crossovers that they favour whilst others never develop an interest beyond very narrow niches.
Some crossovers are actually quite plausible and nearly write themselves (Buffy/Stargate, Buffy/The West Wing and Lord of the Rings/Chronicles of Narnia are three examples that seem, at least to me, to flow naturally). Others need pretty extensive work on the part of the author and some fairly complex canon-surgery to make them work (Star Wars/Star Trek, as much as I love it, is a firm inhabitant of this category).
In the Pony fandom, just about every possible crossover has been tried at least once. These vary from the fairly simple to write (MLP-G1/MLP-FiM), some that need a little work (EqG/Monster High) through to some that requires massive effort to even pretend to be plausible (Friendship is Magic/Warhammer 40,000).
I just had an interesting idea for a Pony crossover, of sorts. In many ways, it's more of an AU than a crossover as it isn't so much combining the worlds as sending one character on a very different journey from the one she went on in canon. However, I think it might be interesting in its own way - My Little Pony/The Wizard of Oz. Instead of landing in the Magical Land of Oz, the twister drops Dorothy Gale into the Magical Land of Equestria (arguably simply somewhere over a different rainbow).
Some Rules for this Crossover
- OCs that are clearly people from Dorothy's Earthly life in the form of ponies or some other Equestrian intelligent species;
- Some variant of the 'quest to go home', with either the Mane Six or the OCs replacing the Lion, Scarecrow and Tin Woodsman;
- Celestia replacing Glynda and Chrysalis replacing Ephibia, of course;
- Who might the Wizard be? A stage magician who is trying to use trickery and stage conjouring to persuade people that he... or she... is a great wizard who can protect them from evil? Step forward The Great and Powerful Trixie!
So, what crossovers would you like to see in Pony fanfiction and what do you think it would need to make it work?
"Toto! The twister must have carried us somewhere over the rainbow!"
"Um... Hello? Welcome to Ponyville! I'm Twilight Sparkle! What... er... who are you?"