In Pokémon Scarlet and Violet, you will come across Ominous Black Stakes hidden around Paldea. However, the game does not make the purpose of these Ominous Black Stakes immediately known, even after you’ve discovered one.
When you come across an Ominous Black Stake, you’ll have the option to pull the Stake out of the ground. Once you do, you’ll see a message that reads, “When you pulled out the stake, it crumbled and vanished!” Nothing else will happen at this time, so you’re left wondering—just what are these Stakes used for?
It’s only later that you learn Ominous Black Stakes are used to unlock four different Shrines across Paldea. These Shrines contain the Ruinous Quartet, or four Legendary Pokémon—Wo-Chien, Chien-Pao, Ting-Lu, and Chi-Yu. There are 32 Ominous Black Stakes total, and eight Stakes for each of the four Shrines. The following are which Stakes you’ll need to unlock each Shrine to get the Legendary Pokémon: