The player and Hop first visit the Slumbering Weald after they've obtained their starter Pokémon in order to chase a Wooloo that had forced open the gate leading to the forest. While going through the forest, the player and Hop ran straight into a thick wall of fog, and are suddenly approached by a mysterious Pokémon. None of the player's Pokémon's moves have any effect on it, and they and Hop are soon knocked unconscious as the mysterious Pokémon envelops them in completely opaque fog. The two wake up and are found soon after by Leon, who also managed to find the runaway Wooloo, and leaves everyone out of the forest.
After Chairman Rose interrupts the Champion Cup by starting the Darkest Day, the player and Hop enter the forest again in order to find the Pokémon they met before, since legend says it once stopped the Darkest Day in the past. The player and Hop eventually find both of the Pokémon described in Galarian legends, and Sonia explains that they are known as Zacian and Zamazenta, which were born somewhere beyond the Slumbering Weald long, long ago. At an altar at the deepest part of the forest, the player and Hop discover the Rusted Sword and the Rusted Shield, ancient artifacts that were once used to stop the Darkest Day. Each of them takes one of the relics, before traveling to Hammerlocke to stop Rose. While the player and Hop confront Eternatus, Zacian and Zamazenta awaken from their long sleep near the altar and rush to join the battle.
During the post-game, the player meets Hop at Slumbering Weald and battles him. After the player has defeated Hop yet again, the two return the relics to the altar, only for Sordward and Shielbert to show up and snatch them. The player manages to recover one of the items, but the two brothers get away with the other one.
Later, Hop pursues ZamazentaSw/ZacianSh to the Slumbering Weald after the twin brothers had driven it berserk, and manages to calm it down by the time player is done catching the other Legendary Pokémon and they and Sonia reach the Slumbering Weald. The Legendary Pokémon then willingly lets itself to be caught by Hop, becoming one of his partners. Hop then requests the player battle him for one last time, in the same place where their adventure first began. Once the battle is over, Hop declares that his new dream is to become a Pokémon Professor, and Sonia offers him a place as her assistant, which he accepts.
A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
On the player's first visit, they are forced to participate in three guaranteed random encounters.
This is followed by a special battle with ZacianSw/ZamazentaSh. In this battle, that Pokémon's name and level are replaced with ??? and the player only has the option to Fight or Run, although they are unable to run. All of the player's Pokémon's moves have no effect, and the wild Pokémon does not use any moves, instead making the fog in the battle thicker and thicker until the player passes out at the end of the third turn.
None of these Pokémon can be caught, as the player has no Poké Balls at this stage of the game.