In the previous versions of Pokémon games, repeated breeding and catching was the only way to obtain a Pokémon of a specific nature. That said, the Sword and Shield version of the games saw the introduction of a new feature that allowed trainers to change the nature of their Pokémon without any hassle. Fortunately, this feature is also available in Pokémon Brilliant Diamond and Shining Pearl.
How to change a Pokémon’s Nature
Trainers can change the nature of their Pokémon by feeding them Nature Mints. There are mints for each nature, and all of them are available in Batlle Tower’s shop. Each mint will cost you 50 BP, which is on the expensive side.
You can only access Battle Tower after beating Elite four and acquiring the National Dex. Hence, the feature of changing a Pokémon’s nature won’t be accessible until you reach the end game. Once you buy a mint, give it to the Pokémon whose nature you wish to change. You can check the nature of your Pokémon by opening the menu and selecting the Pokémon tab. Select the Pokémon whose nature you want to determine and then select Check Summary. A new window will appear, and the first line will indicate the nature of your Pokémon.