In Pokemon Brilliant Diamond and Shining Pearl it is possible to get the mythical Pokemon Manaphy, Jirachi, and Mew. However, there are some requirements in order to get these rare Pokemon. Additionally, all these Pokemon are shiny-locked, so make sure to not waste your time resetting the game.
Now, let’s see how you can obtain Manaphy, Jirachi, and Mew in Pokemon Brilliant Diamond and Shining Pearl.
You can obtain Manaphy through a limited-time Mystery Gift event. This event will end on Feb. 21, 2022, so make sure to receive your Manaphy before then! The Mystery Gift feature is not unlocked right away. You must unlock the feature yourself in the game, and it is quite easy to accidentally miss the NPC that gives it to you.
You will have to defeat the first gym leader Roark before you can access the Mystery Gift. After you beat him go back to Jubilife City, and go into the Jubilife TV building. This building is northwest of the Pokemon center and has a giant TV screen with Chansey on it. Then go to the second floor and talk to the NPC standing on the yellow-orange carpet. He will ask you to answer a question; make sure to select the “EVERYONE HAPPY WI-FI CONNECTION” answer. Then the NPC will unlock the Mystery Gift for you, and you can access this feature by opening your menu.
In the menu select Mystery Gift, and go to “Get via Internet.” Your game will now search for active Mystery Gifts. Select “Manaphy Egg Gift” and press A to confirm. The Manaphy Egg will then be sent to you, and your game will be saved. It will be placed in your party if you have room, or in your PC boxes otherwise.
Now you just have to walk around until the egg hatches. Be warned that this egg takes a lot of steps to hatch. Having a Pokemon with the Flame Body ability can help hatch it faster. In Pokemon Shining Pearl you can find Magby with Flame Body in the underground. As for Brilliant Diamond, obtaining a Flame Body Pokemon will be more difficult. Only Ponyta can have it, but it is a hidden ability, which makes it much harder to find. You can only find hidden ability Ponyta in the grand underground.
Once your Manaphy hatches you can place it in the daycare with a Ditto. Hatching the eggs from this pair will allow you to shiny hunt, and obtain Phiones.
In order to obtain Jirachi you must have save data from Pokemon Sword or Shield on your Nintendo Switch. If you have that then you must progress in the game and beat the first gym leader. Now you can make your way to Floaroma Town.
When you first enter the town you will see two NPCs on the left in a field of flowers. Go up to them and talk to the old man on the left. He will talk about Wishing Stars and give you Jirachi. Jirachi will be level 5 with the ability Serene Grace. Its only moves will be Confusion and Wish.
As for Mew, you must have save data from Pokemon Let’s Go Pikachu or Eevee on your Nintendo Switch. If that is the case then you can talk to the old lady on the right, and she will give you Mew. Mew will be level 1 with the ability Synchronize. Its two moves are Pound and Reflect Type. Now you have two strong psychic Pokemon to use throughout your playthrough.
This is how you can get Manaphy, Jirachi, and Mew in Pokemon Brilliant Diamond and Shining Pearl. I hope this guide has helped you out, and stay tuned for more guides!