In Pokemon Brilliant Diamond & Shining Pearl (BDSP), you will find several Technical Machines (TM) that give you very useful moves. One such move is ‘Flash’, which you get by finding TM70. ‘Flash’ helps you to illuminate caves and will help you access areas that will be inaccessible without it. There are 2 locations in the game where you will find TM70. Flash will help you navigate through dark caves. One such area is the wayward cave, where you will find Gible.
TM70 Location 1: Oreburgh Gate
On your way to Oreburgh City, you will have to go through Route 203 on the northeast side of Jubilife City. At the end of Route 203, you will enter a cave (Oregurgh Gate) as shown in the picture below.
After entering Oreburgh Gate, get ‘Rock Smash’ from the ranger if you haven’t already, as you will be needing it to get ‘Flash’. After you have ‘Rock Smash’ Hidden Move, go to the path on the north side of the ranger as shown below. Break the rocks blocking your path to proceed ahead to reach the underground area.
In the underground area, you will find TM70 behind some breakable rocks as shown below. Break the rocks and take the TM70 to get ‘Flash’.
TM70 Location 2: Veilstone City
Enter the Veilstone Department Store in the Veilstone City. Go to the third floor and purchase TM70 from the woman in the corner as shown below. This will give you the ‘Flash’ Hidden Move.