From Bulbanews, your community Pokémon newspaper.
Serial codes to be distributed in participating stores
Participating stores in Hong Kong and Taiwan will be distributing serial codes for Shiny Tapu Koko from April 28 to May 31, 2017. The codes can be redeemed from April 28 to June 30, 2017.
This Tapu Koko will be level 60, have the Ability Electric Surge, hold an Electric Seed, and know the moves Nature's Madness, Discharge, Agility and Electro Ball. Its original Trainer will be Melemele and it will be in a Cherish Ball.
Tapu Koko cannot be obtained Shiny in the games, making this and the Japanese and Korean distributions the only ways to obtain it at present.
For the complete list of stores, please see the official Chinese Pokémon Sun and Moon site for further details.