From Bulbapedia, the community-driven Pokémon encyclopedia.
The promotional disks are a special collection of disks used with the Pokémon Ga-Olé arcade game that could not be obtained under normal conditions. Special disks (スペシャルディスク) include those available as giveaways, included with items of merchandise, or obtained by playing limited courses in the game. Special disks come in a variety of colors. Trophy disks (トロフィーディスク) are typically transparent purple with a lamé effect and were awarded as participation prizes in Pokémon Ga-Olé events. All of these disks have the collection number "P". Some special versions of disks from sets were also available through promotional campaigns. These versions appear the same as Trophy disks but retain their original set numbering.