This tutorial will show you where and how to obtain TM 36 - Sludge Bomb in Pokemon ORAS (Omega Ruby and Alpha Sapphire)! In order to get this TM, you need to have beaten Brawly and return to Dewford Town, inside the largest house. Once inside, talk to the "new" person who didn't appear before. That person is a true fanatic of Sludge Bomb. The Sludge Bomb Fan will also give YOU one TM 36 for yourself too! Enjoy!
Also, here is a video guide.