From Bulbapedia, the community-driven Pokémon encyclopedia.
In some pre-release material the medals were shown to shine with stars on the corners. However in the final version there is no such star, instead it is just a line going diagonally over the medals.
| A pre-released picture of the medal box
In the coding of the games there is an alternate colored sprite for several Pokéstar Studios opponents, which are presumably Shiny sprites. However it isn't possible to encounter the Shiny sprites in the final version.
| The shiny colored F-00
|| The shiny colored F-00 2