The shiny Tapu Koko that people were complaining about during the Lycanroc promotion is now live via Mystery Gift. To get this guy, just boot up Pokémon Sun and Moon and download it from anywhere with a wifi signal. If you have multiple games, then grab multiple Tapu Koko. They will be excellent trade collateral once the event is over.
Shiny Tapu Koko
Hold Item: Electric Seed
Ability: Electric Surge
Attacks: Nature's Madness, Discharge, Agility, Electro Ball
GTS Status: Shiny Tapu Koko is in a Cherish Ball and has a ribbon that makes it untradable on the GTS or via Wonder Trade. If you receive a Shiny Tapu Koko through either of these services, then it is not the official Mystery Gifted shiny Tapu Koko.
As this is a nature locked event, all shiny Tapu Koko will be Timid. This means this Tapu Koko is meant to be utilized as a fast special attacker. You can save in front of the Mystery Gift man at the Pokémon Center and repeatedly get the Tapu Koko to ensure you get the stats and Hidden Power you want. Ideally, this would most likely be an Ice type Hidden Power, but there are other types that cover some of Tapu Koko's weaknessess (HP Fire for Steel-types for example).