After failing to Masuda Method a shiny Beldum in Black and Black 2, I got a Beldum from a Wonder Trade and decided to try my luck a third time. First I bred a regular Beldum with decent IVs and an Adamant nature to give my future shiny the best chance possible of being competitively useful, then I threw the Beldum in the Daycare with a Japanese Ditto and started the MM.
My sixth egg hatched a shiny.
But wait, there's more! The shiny is Adamant thanks to its parent Beldum's Everstone, and I used the Judge to check its IVs. What was its IV spread? 31/31/31/x/27/31
But wait, there's more! I hatched the remaining 5 eggs from that run, and just for kicks I checked the IVs of the remaining 5 non-shiny Beldums. One had a 31/31/31/x/31/31 IV spread, and another was a PERFECT 6 IV Beldum! That's three Beldums with perfect or near-perfect IVs, one of them shiny, in 5 eggs. I can't remember the exact IVs of the parents, but the parent Beldum had 3-4 perfect IVs while the Ditto had 2-3 so I wasn't using flawless parents.
Goliath the shiny level-100 Metagross is now the pride of my team and the terror of my local multiplayer matches. The 5 IV Beldum was traded to a friend who was planning to use it for his own Masuda Method while the 6 IV Beldum will eventually be traded to my brother. And I don't think I'll ever get that lucky with breeding again.