As part of the opening festivities for the
Pokémon Center Sapporo, an Alolan Rokon was distributed as a present to visitors of the Pokémon Center with
Pokémon Sun or Moon from December 1st, 2016 until January 31st, 2017. That Alolan Rokon will now be distributed at all the Pokémon Centers and Pokémon Stores nationwide in Japan from February 1st, 2017 until March 12th, 2017.
Starting February 1st, 2017, the Pokémon Centers nationwide in Japan will be selling Pikachu dressed in an Alolan Rokon Poncho and Pikachu dressed in a Rokon poncho plushies.
Sources:
http://www.pokemon.co.jp/info/2016/12/161222_p02.html and
http://www.pokemon.co.jp/info/2016/12/161222_p01.html