After you go south through Cycling Road (Route 206), you continue south to Route 207.
In the grass in Route 207, you can catch Geodude, Kricketot, Machop, and (only at night) Zubat.
Go to the left from where you entered Route 207 to find some berry trees.
Go to the right from where you entered Route 207 to find a Honey tree.
Now that you have a bike, you can go down the slope near the cyclist if you want to go back to Oreburgh City, then you can ride back up the slope on your bike (press B to make your bike go faster if needed).
In Oreburgh City, you can now talk to the scientist in the Mining Museum and turn fossils into a pokémon. Fossils can be found in the Grand Underground.
Back in Route 207, if you go south from the Honey Tree and follow the path, you can battle Youngster Austin, who has a level 15 Starly, a level 15 Geodude, and a level 18 Chimchar. You get 576 Pokédollars for winning.
Go up the stairs north of the Youngster, then go west. If you go west past the Hiker, there is hidden Rare Candy at the end of the path.
You can go east to battle Hiker Kevyn, who has a level 15 Geodude, two level 16 Geodudes, and a level 17 Zubat. You get 768 Pokédollars for winning.
Go south from the Hiker to find a Dire Hit.
Go back north, and then you can go east and battle Battle Girl Helen, who has a level 18 Meditite and a level 18 Machop. You get 576 Pokédollars for winning.
Go east from there and follow the path, and you can jump down the ledge and battle Hiker Justin, who has a level 16 Geodude and a level 18 Bronzor. You get 864 Pokédollars for winning.
Go west to find a Super Potion.
West of that, there is a Picnicker and a Camper. You can either battle them separately talking to them from the side, or battle them at the same time by walking between them.
Camper Anthony has a level 19 Ponyta. You get 532 Pokédollars for winning.
Picnicker Lauren has a level 19 Pachirisu. You get 532 Pokédollars for winning.
When you are ready to move on, go east into the cave to reach Mount Coronet.
In Mount Coronet, you can catch Chingling, Cleffa, Geodude, Machop, Meditite, and Zubat. You can use the Old Rod in the water to catch Magikarp.
Go south, then east. If you try to go north up the stairs, there will be a cutscene.
After the cutscene, go north and check on one of the rocks to get a hidden Ether.
Go east down the stairs, and go east around the water, then go south to find an exit to the east. Go through to reach Route 208.