All that is required for the Masuda Method is that one Pokemon comes from a different language game as the other one. So, a Japanese Magcargo and English Drifblim will work just fine. It doesn't matter that they're not in the same egg group.
We have no way of knowing the shiny rate when using the Masuda Method, but the best guess is about 1/683. That could be entirely wrong, however. --- YOU WANT SOME FUNERAL TO GO WITH THAT CAKE? | 3DS FC: 3437 - 4335 - 3104 | | Friend Safari: Panpour, Wartortle, Frogadier |