Few points to keep in mind:1) All transferred Pokemon from the RBY VC console games have their Hidden Abilities 100% of the time. As far as natures go: https://twitter.com/SciresM/status/824115414309421056 2) Only the event Mew given out in the VC games can be transferred any Mew obtained via glitches or other methods are stuck in those games.3) RBY VC mons transferred to Pokemon Bank can become shiny.