Pokémon crossovers

I've been wondering about crossovers. Crossovers can be really weird or really good depending, of course, on how you interpret and merge the two (or more) worlds. It's hard to write, I think.

What other stories, worlds, characters etc. do you think are (or would be) the most interesting, funny or simply best to do a Pokémon crossover with?

Probably every other series on the planet.

The best would be...itself. Well, crossing the manga and anime worlds anyway. Has anybody noticed that Dawn and Platinum look almost exactly alike?

Cross pokemon with digimon! :D

there was once a cross over from yugioh GX to pokemon which was pretty good in my opinion.

Let's try not to bump threads over a month old, all right?