When players start their Pokémon Brilliant Diamond and Shining Pearl adventure, they will only have the regional Sinnoh Pokédex that has slots for only 151 Pokémon. However, like with most Pokémon games, you can eventually unlock the National Pokédex and capture far more Pokémon. That way, you'll likely see many fan-favorite creatures that weren't in the game up to this point. So, just how do you unlock the National Dex? Let's step through it.
How to unlock the Brilliant Diamond and Shining Pearl National Pokédex
Work through these steps to unlock the National Pokédex.
1. See all 151 Sinnoh Dex Pokémon
The Sinnoh region Dex has 151 Pokémon slots in it. You don't have to catch them all to unlock the National Dex, but you do need to at least see all Sinnoh region Pokémon within the game. If you want to be thorough and catch them all, you'll need to trade Pokémon with others to get those version exclusives that don't appear in your game.
You don't need to trade to spot all 151 Pokémon
Source: iMore
You can see all 151 Pokémon from your own game thanks to battles with NPCs and wild encounters. If you're having trouble seeing Palkia or Dialga, the Legendary from the other game, head to Celestic Town and talk to Cynthia's Grandmother in her house. She'll show you a picture of the other Legendary, which will add it to your Pokédex. For instance, I played Brilliant Diamond, so talking to Cynthia's Grandmother made her show me Palkia.
How to spot Drifloon
Drifloon can be one of the trickier Pokémon to spot. Once you've defeated Team Galactic at the Valley Windworks, you need to return to the front of the building on a Friday and Drifloon will be floating there waiting for you. Unfortunately, if you kick Team Galactic out of the building on a Friday, you'll need to wait and come back the next Friday to see Drifloon. Then get it to level 28 to get it to evolve into Drifblim.
The only other way to see a Drifloon in the game is to answer all of the questions incorrectly when going to battle Fantina at the Hearthome City gym and fight all of the trainers leading up to the gym leader. School Kid Mackenzie has it in her party when you face her.
2. Talk to Professor Rowan
Head over to Sandgem Town and enter Professor Rowan's home laboratory. He'll be overjoyed that you managed to see all 151 Pokémon in the Sinnoh region. Eventually, Professor Oak struts into the joint like he owns the place and upgrades you to the National Pokédex. Now you'll be able to see Dex entries for up to 493 Pokémon as you encounter them.
Where to find more Pokémon
Head to the Grand Underground if you haven't seen something yet, or run around the routes until you discover the Pokémon you've missed. Some of the Pokémon can only be hatched from the eggs you receive. So make sure to hatch all of those.
Catch more Pokémon
With the National Pokédex unlocked, you're now able to encounter more Pokémon and add them to your party. There are a lot of new faces, so jump to it if you want to fill that larger Dex up as well.
Catch up to 493 Pokémon
Capture Pokémon and add them to your party as your travel around the Sinnoh region. There are gym leaders to defeat and Team Galactic to thwart along the way to becoming the Champion.
