Keldeo in Crown Tundra is one of the many new and returning legendary Pokémon. And yes, you can find this as a shiny spawn. Learn how to hunt shinies in the game to make this easier. To catch this one, you need to do some work first. The first part of the process is to get through the Crown Tundra story until Sonia shows up and asks you to help find a bunch of footprints. These will need to be found first in order to encounter the Swords of Justice Pokémon, Cobalion, Virizon, and Terrakion.
The process works like this: Go to the location, look for the Pokémon footprints around the zone. They aren’t set spawns, so you just have to hunt them down and look for the sparkles that are similar to that of item sparkles. Once you interact with them, you’ll increase the amount of evidence that you need to gather. Hit 100% evidence by collecting the tracks over time. There are 50 of them in all.
Once you have these, you can move on to hunting other legendary monsters. You need to have Cobalion, Virizon, and Terrakion in your party before you go hunting for Keldeo in Crown Tundra.
Your target spawn location is in the south the region at Ballimere Lake. Go there via the fast travel system and look for the island marked below. You’re after a certain location with a cooking pot beside a small tree on this island. The location is to the southwest of the Dyna Tree Hill map point.
To make Keldeo spawn, pitch Camp here and cook any kind of Curry dish. It doesn’t matter what you cook as long as you complete it. Exit the camp screen after this and the legendary will spawn.