Pokémon Style (ポケモンスタイル) is an app for Apple iOS and Google Android for users in Japan. It is available on the Google Play store and the Apple App Store as a free app that allows people to download wallpapers and icons for their smartphones. It requires at least Android 4.0 or iOS 7.00. It was released on Android on February 16th, 2015.
The app updates twice a month on the second and fourth Thursday's of each month with new designs. Some of the styles are free but other premium styles cost 200yen. A free promotional
Pikachu Kisekae Set (ピカチュウのきせかえセット) is available for all those that download the app.
A special promotion is also being held for the premium sets from February 16th, 2015 until February 25th, 2015. The Hoenn starters set, the Eevee set, and the Xerneas and Yvetal set are being sold for 100yen.
Source:
http://www.apppokemon.com/style/