So in Pokemon FireRed, the Pokedex entry for Kadabra says "It happened one morning - a boy with extrasensory powers awoke in bed transformed into Kadabra." This is an interesting aspect of the Pokemon world not really covered in the media outside of one generation of the games, but in the world of Pokemon, people can apparently just spontaneously transform into Pokemon for no particular reason. Most would find that terrifying, but if you're a sick freak like me, it's probably just another reason to wish you lived in the world of Pokemon just like you did since you were six. Poor Misty though, we all know how she feels about Bug-Types. And now she is one. At least she's turning into a shiny though, so it's not all bad.

Version where she's turning into a normal non-shiny Caterpie: http://www.furaffinity.net/view/23597148/