Solgaleo and Lunala are the box Legendaries for Pokemon Ultra Sun and Ultra Moon, so naturally, it stands to reason that you would get one of them in their respective game. However, there are actually two versions of the box Legendary in your game, leaving you with the extra Pokemon you need to fairly trade with another version — though you’ll need to follow an obscure sidequest found near the end of the story to get it.
So how do you catch the original Solgaleo or Lunala, and how do you go on to find their stunt double? Let’s dive in!
Solgaleo and Lunala become catchable in their respective versions after traveling to Ultra Megalopolis and defeating Necrozma at the end of the game. They’re not found at the Altar of the Sunne or Moone, though, like they were in the originals.
Instead, travel to Iki Town on Melemele Island and make your way up towards the Ruins of Conflict. Right before the bridge where you originally met Lillie, you’ll find her standing next to Solgaleo or Lunala, depending on your version. She asks you to challenge them to a battle in order to capture and travel with them.
Be sure to save before the battle in case you accidentally knock them out or want to soft-reset for better stats. Also, remember to bring a Pokemon with Synchronize in order to get the Nature you want. Catch it with the skillful toss of a Pokeball and Solgaleo or Lunala is all yours.
Now that you have your box Legendary, you can go about getting the duplicate by first finding Cosmog through an obscure sidequest.
How to Find Cosmog in Pokemon Ultra Sun and Ultra Moon
With the newly captured Solgaleo or Lunala in your party, head back to the Altar of the Sunne or Moone respectively and interact with the Ultra Wormhole at night in the real world. (In Ultra Sun, this is the same time as night in-game. For Ultra Moon, do this during the in-game day.) You’ll find a new option in the pop-up menu:
Go to the reverse world
Select the new option to travel to a different world where day is night and night is day. In the reverse world, use the Poke Ride Charizard to fly to the Lake of the Sunne or Moone on Ula’ula Island. From here, head inside the ruined building atop the lake and follow the path all the way to the end.
Once you reach the altar inside, Solgaleo or Lunala will call out to the heavens and a mirage of the opposite version’s Legendary appears before them. After witnessing the event, you find Cosmog sitting atop the Altar. Simply interacting with it adds it to your team, so you don’t actually have to battle it. You also receive the Z-Crystal for the box Legendary of the opposite version.
Note that you won’t find Cosmog if Solgaleo or Lunala is currently fused with Necrozma, nor will you find it if you come at the wrong time of day. Also, note that the Altar of the Sunne or Moone will only be fully accessible after beating the game.
Cosmog evolves into Cosmoem upon reach level 43. At level 53, Cosmoem finally evolves into another Solgaleo or Lunala. It’ll be the same as the box Legendary, so you’ll essentially see doubles, but you’re bound to find someone willing to trade one of their extras for one of yours.
With these Legendary Pokemon in your team, you’re that much closer to completing the regional Pokedex. For more on the latest mid-gen remakes, be sure to check out the rest of our Pokemon Ultra Sun and Ultra Moon guides.