You’ll have to meet specific evolution requirements for Pokémon if you want them to reach their final transformation. Many Pokémon in Pokémon Brilliant Diamond and Shining Pearl will need an evolution item or to know a particular attack if you want to evolve it. For those trying to get Growlithe into Arcanine, you have to follow a specific method. Here’s what you need to know about evolving Growlithe into Arcanine in Pokémon Brilliant Diamond and Shining Pearl.
You’ll need to capture a Growlithe first. If you’re having trouble with that, you’ll only be able to find this Pokémon when you complete the game and you’ve received your National PokéDex. At that point, Growlithe should begin spawning in the Grand Underground, namely the caves with lava, the ones with sand, and the Typhlo Cavern. It’s also important to note that Growlithe is a Pokémon Brilliant Diamond exclusive Pokémon.
After you have Growlithe, it comes down to giving it a Fire Stone. Your best bet to find Fire Stones is to search for them in the Grand Underground through the fossil digging minigame. You can increase your chances of finding evolution items by finding the Digletts and Dugtrios that spawn in the passageways of the Grand Underground. When you give Growlithe the Fire Stone, it should immediately evolve.
If you’re playing the Pokémon Shining Pearl version of the game, reach out to another player playing Pokémon Brilliant Diamond. So long as they trade you the Growlithe, you’ll be able to evolve it in your game using the same method.