How to find Alola’s Light Trio in Pokémon Scarlet and Violet

The Light Trio is known as such because Solgaleo, Lunala, and Necrozma are known for bringing light to Alola when they were born. You can catch them in Pokémon Scarlet and Violet by getting their respective Treats from Snacksworth in the Hidden Treasure of Area Zero DLC; in both versions, you'll need to complete Group Blueberry Quests to get the Necrozma Treat, while depending on whether you have Pokémon Scarlet or Violet, you'll get the Solgaleo Treat or Lunala Treat by doing Solo BBQs and the other by doing Group BBQs.

Solgaleo

Solgaleo's location is pretty simple; Snacksworth mentions visiting Paldea's Pokémon League building; Solgaleo appears on the top of the building, where you fought the champion; it will have the Full Metal Body ability, preventing its stats from being lowered; it also has the moves Metal Burst, Wild Charge, Solar Beam, and Flare Blitz; Wild Charge and Flare Blitz will damage Solgaleo with recoil, so keep that in mind when weakening it to catch.

Lunala

Snacksworth was looking into the sea on a beach during the sunset, meaning that he was on a beach in the West when Lunala appeared. Lunala will be at the end of the river south of Casseroya Lake, just before reaching the beach; it will have the Shadow Shield ability, reducing damage received when at full health (with some exceptions like Mold Breaker or fixed damage moves); it will also have the moves Psychic, Moonblast, Phantom Force, and Dream Eater; Dream Eater will not have effect if your Pokémon isn't asleep and Lunala has no sleep inducing moves in the fight.

Necrozma

Snacksworth's hint is pretty vague; all you can go by is that it was near some waterfalls and that there were a lot of Sawsbuck nearby; one place that fits that description is Socarrat Trail, Necrozma will be above the rock where you can find Ting-lu's shrine, next to the waterfall's origin; Necrozma will have the Prism Armor ability, which reduces the damage of super-effective moves (in this case, Bug, Ghost, and Dark type); it will also have the moves Stored Power, Rock Blast, Iron Defense, and Power Gem; Stored Power will become stronger as stats are increased, and Iron Defense will raise its Defense by two stages.