The Diploma is a recurring item in the Pokémon series awarded upon completing each game’s Pokédex. The in-game document recognizes the enormous effort that it takes to fill out one’s Pokédex, and it’s also delivered by an NPC representing Junichi Masuda, the director of Pokémon’s primary developer Game Freak. Here’s how to earn the Diploma in Pokémon Brilliant Diamond and Shining Pearl.
First, you’ll have to complete the Sinnoh Pokédex, which in turn earns you the National Pokédex. To complete the Sinnoh Pokédex, you only have to see every type of Pokémon in the Sinnoh region; don’t worry about catching them. After seeing every Pokémon in the region and acquiring your new Pokédex, head over to the Hotel Grand Lake, where you’ll be able to meet Junichi Masuda. Masuda will reward you with a certificate congratulating you on seeing every Pokémon in the Sinnoh region.
One issue you may encounter when trying to see every Pokémon is that you can only see either Dialga or Palkia atop the Spear Pillar, depending on which version of the game you’re playing. However, regardless of which Legendary you faced, you can see the other one by visiting Cynthia’s family’s house in Celestic Town, where you’ll be shown a picture of Dialga if you’re playing Shining Pearl, and Palkia if playing Brilliant Diamond.
If you complete the National Pokédex, meaning you actually catch and not just see every Pokémon in the game (aside from unreleased Mythical Pokémon like Deoxys, Arceus, Darkrai, and Shaymin), then you can find Masuda again at the Hotel Grand Lake, where he’ll give you a separate certificate featuring Dialga and Palkia certifying you’ve completed your National Pokédex.
