There are more TMs that you can find in Pokémon Brilliant Diamond and Shiny Pearl that you can give your Pokémon to teach them moves that they wouldn't otherwise learn as you level up. For those looking for the Flash, TM 70, you'll have to do a little bit of everything to locate it. Here's what you need to know to find this Flash's location in Pokémon Brilliant Diamond and Brilliant Pearl.
You can find Flash shortly after defeating the first Gym Leader in Ore City, Roark. After beating Roark, you will be able to use HM rock smash in the world, allowing you to break the boulders blocking your path.
Return to the cave between Oreburgh City and Route 203. Make your way to the cave entrance that connects to Route 203, but go north from where the Hiker who smashed the rock for you is located. Now you will be able to destroy the rocks blocking your path.
Proceed along the path and you will find a ladder. Drop down into the next area and on the right hand side there will be a Poké Ball on the ground. You will have to break two rocks using the rock smash in your way. When you reach the Poké Ball, you will receive the TM 70, Flash.
