how to remove boulders in your secret base platinum

[pete]

how do you remove boulders in your secret base in pokemon platinum

[Zidarose]

From: Pokemon Platinum The Underground

Capture the Flag!
As mentioned earlier, you can run into other Players and your friends in the Underground. By finding their base, grabbing their flag and returning to your own, you can clear away the boulders inside your base. This will also upgrade your own flag and allow you to have more decorations out inside your Base. In the beginning, when you have yet to collect any flags, you can have a maximum of 10 decorations out, but you cannot stow any boulders. When you collect a flag, you can have 2 additional decorations, stow 1 boulder and receive the Bronze Flag. At 3 flags, you can have a total of 15 decorations, remove 5 boulders, and receive the Silver Flag. Once you capture 10 flags, you will also unlock a new feature in your Underground PC, allowing you to use it to find your buried spheres as well as buried treasure and traps hidden on the Undergound Map. You can stow 5 more boulders as well as you receive the Gold Flag. The final upgrade comes at 50 captured flags. You can now stow away all boulders and you receive the Platinum Flag.