I have 2 best-the first was a shiny Pumpkaboo that turned into a Gourgeist which is awesomely Halloweeny as a shiny. The other is on a new game I started, sent out a Sandile and got Reshiram. It's probably a hack or clone but don't care :).
I once got a Shiny Japanese Budew that came with an Assault Vest when clearing out my Switcheroo Klefki hatchlings. It was a random encounter one in Kalos, but it was still really nice to get, especially with the attached item.
~ Space for Rent ~ Official Zorua of the Pokemon X / Y boards.