A Pokemon that is shinylocked is unable to be legitimately obtained shiny in the game(s) they are listed under. The game is programmed so that they will never appear as shiny. This practice started in Pokemon Black and White and has continued up to the most recent games (Ultra Sun and Ultra Moon).

A Pokemon being shinylocked in one game does not mean it will be shinylocked in all subsequent games.

Pokemon Black/White & Black 2/White 2

• Victini
• Reshiram
• Zekrom

Pokemon X & Y

• Articuno
  
• Zapdos
  
• Moltres
• Mewtwo
• Xerneas
• Yveltal
• Zygarde

Pokemon Omega Ruby & Alpha Sapphire

• Kyogre
  
• Groudon
• Rayquaza
• Deoxys

Pokemon Sun & Moon

• Tapu Koko
  
• Tapu Lele
• Tapu Bulu
• Tapu Fini
• Cosmog
• Solgaleo
• Lunala
• Nihilego
• Buzzwole
• Pheromosa
• Xurkitree
• Celesteela
• Kartana
• Guzzlord
• Necrozma
• Zygarde

Pokemon Ultra Sun & Ultra Moon

• Tapu Koko
  
• Tapu Lele
• Tapu Bulu
• Tapu Fini
• Cosmog
• Solgaleo
• Lunala
• Zygarde

The following Pokemon have been shinylocked in all games they appear in and have not ever had their shiny form distributed via an event*: Victini, Keldeo, Meloetta, Zygarde, Hoopa, Volcanion, Tapu Lele, Tapu Bulu, Tapu Fini, Cosmog, Cosmoem, Lunala, Solgaleo, Necrozma, Magearna, Marshadow, Zeraora

*The listed Pokemon have not had their shiny forms available via any event prior to February 12th, 2018 (the day this list was made); it is possible that they will have their shiny variants distributed in a future event.