Energy Ball is a powerful grass-type move that you can find after completing the main game. This move has a massive 90 power and 100 accuracy that makes it a force to reckoned with. Getting this TM, however, is no simple task and it will take a long time. Here is where you can find Energy Ball in Pokémon Brilliant Diamond and Shining Pearl.
Before you can get your hands on this TM, you will first need to complete the game. This is done by defeating the Elite Four and becoming the Sinnoh Champion. After completing the main game, you will be allowed to enter the Battle Zone. To get there, head to Snowpoint City and talk to the captain there to set sail. Once you reach the Battle Zone, you will see two NPCs that are blocking the path to the north. To make them move, you will need to complete the Sinnoh Pokédex. This means you will need to see every Pokémon, not capture them.
Once all of that is done, the NPCs will move out of your way and you can take Route 225 up to the Survival Area. You will know when you reach the Survival Area thanks to the PokéMart and Pokécenter in the area. Now that you have reached the Survival Area, head east to Route 226. You will be climbing a bunch of different rocks to reach the TM.
Start by using Rock Climb on the rocks the area east and a little south of the Survival Area. This will lead you to a trainer with green hair. Take the rocks on the platform leading down. Head east and use Rock Climb on the rocks that go up the cliff. You will see two trainers at the top; a dragon trainer and a bird handler. Defeat them both and use Rock Climb on the rocks on the other side of them. This will lead you to the TM on the platform below.