OH...eheheh.
The Masuda method is the fairly-confirmed way of getting nonchainable shinies at an easier rate. For Rotom, because you can SR for it, I don't suggest it, but it's mindless. If you breed two pokemon of different nationalities, like a Japanese Ditto and an English Cherubi, then the game picks four shiny numbers and not one. Your shiny odds go from 1/8192 to 1/2048. The odds are still low, and your PC fills up quickly. Regardless, some people report finding shinies before 200 eggs. I, personally, can't say that...