This is a guide for A returning feature in Pokemon Brilliant Diamond & Shining Pearl is the Grand Underground- a feature that lets you explore caves deep under the Sinnoh region, with items galore for you to get as well as special versions of Pokemon that would be much harder to get on the game’s surface world..
The thing is if you’re just mashing through the dialogue, the game’s tutorial doesn’t really go over the nuances of operating the underground in Pokemon – or explain how any of the new Pokemon caves even work. The NPC who first gives you the Explorer’s Kit (next to the Pokemon Center in Eterna City) will give you a rough tutorial of the basics too- so make sure to come back to him as well for a step-by-step look.
The Basics of Pokemon ‘s Grand Underground
The Underground is a giant sprawling maze under the Sinnoh Region. An important thing to note here is that it’s not completely interconnected- some parts of the map will lead to their own underground, so you’ll want to take note of which Caves are appearing and from where you accessed them if you’re targeting certain Pokemon.
If you get lost, don’t worry- pressing in on the right thumbstick zooms out the map, so you can decide where the next room you wanna go to is instead of being stuck with the zoomed-in view.
The other thing is your badges- the Grand Underground changes every time you get a new badge, with the average level of each Pokemon going up. Some Pokemon won’t be available without a minimum number of badges too, so make sure to keep checking back every single time to see when some rare Pokemon might make an appearance.
Mining in the Grand Underground
One of the poorest explained parts, a key part of the Grand Underground is the mining. You’ll notice that certain points on your map have orange markers, where the game tells you there’s treasure. That being said, you’ll probably find yourself frequently running towards these walls and getting nothing, which might be frustrating.
You can press R on your controller to let out a radar pulse, which will mark any wall with treasure on it with a sparkle. Note that the same square of the wall can have multiple treasures in it, so be sure to check each wall.
Once you start the mining minigame, you’ll see your board. Remember the layers go Brown (nothing).>Tan> Grey>Boulder. Also take note of the crack along the top of the screen, which tells you how many moves you have left.
For clusters of boulders it’s better to just use the sledgehammer, since you’ll open up more at once without wasting moves. When you click on a block, you may notice other blocks getting cracked around it- don’t waste your swings hitting the cracked blocks, simply hit a normal block next to it and will clear the other blocks that have cracks in them.
Look out for Digletts
You’ll notice various Digletts and Dugrio hanging out in the tunnels, leaving shiny objects before they run. These fill up the Diglett gauge underneath your map. and filling up the gauge ensures you get a better chance at finding treasure boxes or even Shiny Pokemon. Think of it like a pity system in a gacha- so pick it up every chance you get.
Talk to NPCs And Secret Bases
Make sure to talk to NPCs in the Grand Underground as well. Some of them are merchants who will trade gems with you for various rewards, which you’ll want if you need more Digger Drills to build a new Secret Base.
Speaking of Secret Bases, you may be wondering how to get cool statues to decorate your base- these are all found via the treasure boxes in the Grand Underground, so there’s no short answer outside of “get digging”.
Pokemon of the Grand Underground
One thing that is new to the Grand Underground is the Pokemon Caves, each one representing a different biome. The Pokemon here are way more valuable than Pokemon on the surface for a multitude of reasons- one, you have better chances of finding Pokemon with egg moves here, so definitely check here first if you’re not keen to chain-breed a Pokemon.
The next feature is probably the most obvious- the average level of Pokemon in the Underground is way higher than surface Pokemon, so this is a good place to pick up a new party member if you don’t want to spend an hour catching them up to your team level. Note that you’ll probably want to unlock Ultra Balls first, since many of the more advanced species like Absol and Scyther will have much higher catch rates than you’re used to.
You can also get fossil Pokemon via the digging minigame too, so definitely spend some time here if you’re looking to pad out your Pokedex.
That’s about it for the Grand Underground- it may seem intimidating at first, especially if you’re underleveled. But investing time in the Underground is a good way to either boost your existing team with a good XP source or even find a new Pokemon to fill out a niche you didn’t know you were missing.