Pokemon Shiny Hunting Wikia

A Shiny Locked Pokémon cannot be shiny unless it is obtained from an event. These were introduced in Black and White. As a result, any Pokémon before those games can be shiny (barring most events).

The Pokémon in the following list cannot be encountered as shiny under any circumstances.

Victini Reshiram Articuno Kyogre Tapu Koko Tapu Koko
Reshiram Zekrom Zapdos Groudon Tapu Lele Tapu Lele
Zekrom Moltres Rayquaza Tapu Bulu Tapu Bulu
Mewtwo Deoxys Tapu Fini Tapu Fini
Xerneas Cosmog Cosmog
Yveltal Cosmoem Cosmoem
Zygarde Solgaleo Solgaleo
Lunala Lunala
Necrozma Necrozma
Zygarde Zygarde
All Ultra Beasts All Totem Pokemon

In ORAS, all Mirage Spot Pokémon, including Legendaries, can be shiny. In USUM, all Ultra Wormhole Pokémon, including Legendaries and Ultra Beasts, can be shiny. In addition, the Ash Cap Pikachu in USUM is set to be shiny locked, however, due to an oversight, it checks Pikachu's PID against the Player's TID and SID, instead of Ash's TID (170715) and SID, meaning that, unless the player has the same TID and SID, it can be shiny; it does not, however, have a shiny sprite, and will appear normal, with a shiny animation.