When you reach the end of the game and defeat the Elite Four in Pokémon Brilliant Diamond and Shining Pearl, the next step is to unlock the National PokéDex. You can only do this if you encounter all of the original Pokémon from the Sinnoh region. They’re scattered all over the game, many of them appear in trainer battles, and some of them are in the wild at specific routes. However, the legendary Pokémon counts well, which means you need to find Palkia for the Pokémon Brilliant Diamond version. In this guide, we cover how to get Palkia for your PokéDex in Pokémon Brilliant Diamond.
You need to make your way to Celestic Town. You can find this town close to the center of the map, along Route 210 and to the right of Mt. Coronet. When you arrive, head to the north part of the town and look for the large building overlooking the ruins on the third layer of the city.
Inside the home, speak with the elderly woman on the left side of the room. She’ll talk to you about reading old books, and eventually, she’s going to show you a picture of Palkia. When you register this information into your PokéDex, ensuring you’re one step closer to unlocking the National PokéDex.