I have, but only with Game Shark... it is blue instead of Purple... looks like the Mew at the begining of the original Pokemon series, first season during opening.....
If you list Shineys, dont list ones bred in GSC, my list woulda taken a page and a half... okay not that many, but I had over half of the GSC Pokemon shiney through Duping and breeding with Ditto.
FYI on FRLG, when you are veiwing the Pokemon that is shiney, or you suspect is shiney, the box that the Pokemon is in on the staus screen (stats, moves, nature, ect..), it has a star in the upper right hand corner.