Ghost-type trainers in Pokémon Brilliant Diamond and Shining Pearl should head their way to Celestic Town during their playthrough as its nearby route provides a powerful move TM30 Shadow Ball. Here’s how to find it.
This powerful dark move in Pokémon Brilliant Diamond and Shining Pearl can be found on Route 210. You can access it after receiving a unique potion from Cynthia and clearing out the Psyduck barricade that blocks your path. You will also need the hidden move Defog to proceed through this otherwise hidden landscape. You can search for it in the Great Marsh in Pastoria City after beating the Veilstone City gym leader. Route 210’s east of Celestic Town and northwest of Solaceon Town.
Once you’re on Route 210 from the eastern side, go past the first patch of grass and go up the stairs. Past the first wooden bridge, you’ll see a slimmer crossing that you can’t walk on. In a dangerous move by your protagonist, ride your bike and then follow the passage to the left and down. You’ll see some boulders in your way. Use the hidden move Rock Smash to blast through them. The TM30 Shadow Ball will be waiting for you on the other side.
Shadow Ball’s power and accuracy are very effective at a rate of 80 and 100 respectively. It will also lower the target’s special defense stat, which would be perfect for a Pokémon like Alakazam or Gengar.