Is your feature request related to a problem? Please describe.
Picture this, you found a Shiny Diglett, but you don't want the Diglett; now, you could sell it to someone else in exchange for the shiny you want, OR you could be allowed to remove the shininess from the Diglett and instead put it on your Arcanine.

Describe the solution you'd like
The addition of a configurable option to enable (or disable) the ability to turn a shiny Pokémon into a normal Pokémon, and obtain the Shiny Item to use it on another, or to sell to other players.