In Pokémon Scarlet and Violet The Indigo Disk, not every Legendary Pokémon is part of some grand story quest. Some, like Latias, are just hanging out and waiting for you to give them a snack before you can catch them.
As you complete the DLC’s story, and plenty of Blueberry Quests (BBQs,) you can encounter a number of Legendary Pokémon thanks to an NPC who loves traveling and food! After beating The Indigo Disk’s main story, you’ll unlock a new NPC named Snacksworth. He appears at the entrance of Blueberry Academy and tracks your progress through BBQs. Every time you complete a BBQ milestone, you can talk with him and get a new snack, along with a hint at where to encounter the Legendary Pokémon that the treat is named after.
Pokémon Scarlet and Violet The Indigo Disk: Latias location and unlock requirements
Latias doesn’t have a lot of depth to its search. It is simply floating around at the very edge of South Province (Area Four) at the bottom of some staggered ledges. It will do a cute set of animations as you approach (much like how Lugia’s encounter features it swimming with a new model) before you begin the battle and catch it.
After catching Latias, head back to Snacksworth, or go back to grinding BBQs to unlock your next Legendary Treat and riddle. Just be warned, the order you receive them is randomized, so you likely won’t be seeing Latios next and could just end up finding Articuno.