I had a shiny Bellossom.
I can no longer find it. I checked every game, and it wasn't on any of my game cards. I didn't delete anything at the time I was checking either, so it isn't like I absentmindedly deleted the game with it. It might be on my old Colosseum game, but I've lost that particular memory card.
I have a theory that my excessive cloning in Emerald may have something to do with it, because my Nidorina went missing in the same way as well.