i want it so i can trian my electriver in victory road and its a weakness coverage
You can find TM 31 Brick break in oreburgh gate a t the lowest floor. I believe you need Strength and Rock smash. You could also find it at the Battle Frontier but I'm assuming that you haven't beat the game.
There are two ways to get the Brick Break TM:
At the Battle Frontier for 40 BP. You can obtain multiple copies this way.
In Oreburgh Gate B1F. The earliest point when you can get this TM is after defeating Gardenia. You will need the Bicycle and the Rock Smash HM.
Here's a tutorial with text directions + screenshots to help you reach the exact location: https://guidestrats.com/pokemon-platinum-tm31-brick-break/
I'll also add a screenshot of the exact location in Oreburgh Gate below, taken from the same tutorial.
(Source)
Falcons right except for the fact you don’t need Strength for Brick Break. Just Rock Smash and a Bike