How to find Hoenn’s Super-ancient Pokémon in Pokémon Scarlet and Violet

In the Hidden Treasure of Area Zero DLC from Pokémon Scarlet and Violet, you can catch some Legendary Pokémon from previous games, including the main Legendaries from the third Generation; depending on which version you have, you can receive the Kyogre Treat or the Groudon Treat from Snacksworth after completing Solo Blueberry Quests, and the other from Group BBQ's, while the Rayquaza Treat is locked behind multiplayer Group BBQ's for both games.

Kyogre

Snacksworth's story will describe one of the Ten Sights of Paldea, the Gracia Stones to be precise; Kyogre will be swimming in front of the stones; it will have the Drizzle ability, which will make it rain to boost its Water-type moves; it will also have the moves Muddy Water, Ice Beam, Sheer Cold, and Aqua Ring; Sheer Cold has a small chance to hit but will be a one-hit KO if it lands.

Groudon

Groudon's hint points to Alfornada Cavern, the cave system below Alfornada; Groudon will be on the top level near a Terastalized Pokémon; on the map, it would be just outside of Alfornada, in the southeast; it will have the Drought ability, which will summon Harsh Sunlight to weaken your Water-type attacks; it has the moves Earthquake, Hammer Arm, Fissure, and Rest; Fissure is a low-accuracy one-hit KO attack, and the move Rest fully heals it.

Rayquaza

Rayquaza's story talks about climbing to a high point and a sea of clouds; the place is the outer rim of the Great Crater of Paldea, on the side of the South Province (Area Three), climb to the top, and Rayquaza will be in that area; Rayquaza will have the Air Lock ability, preventing any changes in the weather; It also has the moves Dragon Pulse, Hyper Voice, Rest, and Fly.