How to change Dialga’s forme in Pokémon Legends: Arceus

gamepur.com:

You can catch several legendary and mythical Pokémon in Pokémon Legends: Arceus. A returning Pokémon that many trainers are excited to see is Dialga, and in this game, it comes in a unique forme. Like Giratina, Dialga will now have two forms, and you can change between them while playing the game. In this guide, we cover how to change DIalga’s forme in Pokémon Legends: Arceus.

You’ll be able to encounter this legendary Pokémon after you complete the game. You’re better off thinking about doing this after completing the main Pokémon Legends story, so work through it.

After you reach the end of the game, you’ll unlock access to a specific request 89, The Diamond Clan’s Treasure. Once you receive that request, you’ll need to meet with the leader of the Diamond clan, Adam, who is waiting for you in the Obsidian Wastelands. When you reach them in the Obsidian Wastelands, they will change you to a battle, which means you’ll want to bring the best Pokémon you have available to defeat him. After defeating them, you’ll receive an item called Adamant Crystal.

Return to your inventory and head to the Key Items page, where you should find the Adamant Crystal. Click on it with Dialga in your party, and you can transform it. The Altered Forme is the one from Diamond and Pearl, and the Origin Forme is the one you see in Pokémon Legends. You can freely swap between these two formes at will, and while Dialga is in its Altered Forme, it will be holding the Adamant Crystal. Take the crystal away if you want to swap back to its Origin Forme.