I don't know how much research has been done in this glitch, cheat or whatever you like too call it.
It's the classic "Catch Blue Ditto" trick (send red Gyarados to RBY, teach it mimic, battle Ditto, mimic transform, transform to Ditto and wait for Ditto to transform to Gyarados, then catch ditto, trade to gsc and watch it -it's a shiny!) which I have explored.
I wondered if you could change the DV's of *your* pokémon, instead of the Ditto. To test it, I had Gyarados, and a Mew with transform.
I battle Ditto w. Gyarados. When the transforming is done, and the Ditto now supposedly has Shiny DV's, I send in Mew. Mew used transform two times, then I exited the Battle. I boxed mew (if the DV's had changed, then, logically, the stats would also change when Mew was boxed), but no change. Traded it over to GSC, still no change -it remained un-shiny.
So... I still think works. I think that you can let Mew copy Ditto's DV's, but the effects end when the battle is finished. Or, if they remain, I probably did it wrong. I need your help to figure out how to do it. Imagine that you control Shiny Ditto, and that Mew is the pokémon you will make shiny, and then catch. I think it would work, though my very limited research proves otherwise. If it works, though, you could get any of the 151 originals (which learn mimic) as shinies. *If* it works.