First,go to the Sekra Range.Keep on going untill your close to the Fiore Temple.When your close to the stairs to Fiore Temple go to the right.Then you'll see a big boulder.You will need a Golem,Poliwhirl,and Blaziken.Use Golem's field move to crush the boulder.Then you will see a flower.USE Poliwhirl's field move to make the flower grow.Then climb the flower.Then you will see a cave.Go in the cave.When go in the cave if you keep going forward.Then you will see a giant ice cube.Use your blaziken field move to meilt it.Then keep going forward.Then you will see anther cave.Go in it.then you will see Regirock.Enjoy.Note:this will only work if you beat the game.