Instructions
Fight Jasmine at Olivine City Gym and earn the Mineral Badge. Go to Ecruteak City and visit the Pokemon Center if you need to heal your Pokemon or change your Pokemon squad. Leave the city and head east to find Route 42.
Head down Route 42 to find Mt. Mortar. Enter Mt. Mortar and into level 1F. Your character will bump into a Pokemon trainer, who will apologize, and give you HM04, which gives you the Strength move. Teach Strength to the desired Pokemon in your roster. Use the Strength move to move large boulders out of your way as you travel through the mountain.
Head north through level 1F, up the stairs, and through the door on the wall to enter a horizontal path. Turn left and walk up the stairs. Continue going up the stairs until you see a ladder that leads down. Climb down the ladder to get an Ether, then go back up it. Go back down the stairs. Turn right, and you will run into the trainer Poke Maniac Harrison. Battle the trainer.
Go up the stairs next to where you encountered Poke Maniac Harrison to get to floor 1F-2; find another ladder and a Revive item. Go back down the stairs to return to Poke Maniac Harrison. Find the middle stairs and go up them to get to floor 1F-3.
Move the boulder blocking your path with your Strength move and push it in front of where you are standing. Go north on the path to find another set of stairs on your left. Follow them to get an Ultra Ball. Go back down the stairs, and go north. Head to the east to get the Max Potion. Continue heading east to find a downward path, and a flight of stairs. Go down the path to find the Escape Rope. Go up the stairs and then walk north to find a Nugget. Go north and then east to find the south-facing stairs. Go up the stairs to battle trainer Super Nerd Markus.