After you pass through the Zubat Roost and Muraille Coast, you arrive in Ambrette Town.
When you first arrive in Ambrette Town, your neighbor will show up and recommend that you visit the Fossil Lab in case they know something about Mega Evolution.
Go down the stairs and talk to the woman near the Pokémon Center. She gives you TM94 Rock Smash.
There is a narrow path to the right of the Pokémon Center. Go up that path to find a Heart Scale.
Go south from her to find a punk who will give you different types of poké ball in exchange for a regular poké ball. He'll do up to one trade per day.
In the house to the left of the punk, the blonde girl asks to see pokémon with a stat above a certain value. She'll give you an item if you have one.
There is a hotel in the south end of town. Talk to the girl on the right to get TM96 Nature Power. Upstairs, the girl in the middle room will give you a different ribbon depending on the day of the week. She'll put it on the pokémon that you have in the first spot.
In the room on the right, you find Mr. Bonding. He gives you Sp. Def Power.
Go into the Fossil Lab and go toward the right side. Your neighbor will arrive. The two of you will ask about Mega Evolution. They don't know anything about it, but they suggest that pokémon revived from fossils might hold a clue. They say to go to Glittering Cave to talk to the assistant there who knows how to use the machine that revives fossil pokémon.
The entrance to Glittering Cave is east of the Fossil Lab. If you talk to the assistant, he says that you'll have to ride a Rhyhorn to reach the cave.
Talk to the girl on the right to get a Rocky Helmet. If a pokémon holds a Rocky Helmet, then any physical attacks that hit the pokémon will cause some damage to the attacker.
Use the east exit to reach Route 9: Spikes Passage.