After you defeat Commander Mars in the Valley Windworks, the path north through Route 205 is open.
In the grass in Route 205, you can catch Bidoof, Buizel, Pachirisu, and West Sea Shellos, and you can use the Old Rod in the water to catch Magikarp.
Trainer Battles and Items
North of the bridge, you can battle Camper Jacob, who has a level 14 Ponyta. You get 504 Pokédollars for winning.
Go left through the tall grass, then go north up the stairs. To the right, there is an X Attack.
North of that, you can battle Hiker Daniel, who has two level 11 Geodudes, a level 11 Bidoof, and a level 11 Machop. You get 616 Pokédollars for winning.
East of the hiker, you can battle Aroma Lady Elizabeth, who has a level 14 Budew. You get 728 Pokédollars for winning.
North of the Aroma Lady, you can battle Picnicker Siena, who has a level 12 Shinx and a level 12 Pachirisu. You get 480 Pokédollars for winning.
North of the Picnicker, there are two berry trees. You can pick the berries and plant new ones, and check on them again to water them.
West of there, you find a Poké Ball.
Go back to the Hiker and go north, where you can battle Camper Zackary, who has a level 14 Geodude. You get 504 Pokédollars for winning.
Go north across the bridge and you can battle Hiker Nicholas, who has a level 14 Onix. You get 728 Pokédollars for winning.
North of the Hiker, you can battle Battle Girl Kelsey, who has a level 15 Machop. You get 540 Pokédollars for winning.
Southwest of the Battle Girl, there is a Repel.
Northeast of there, you can battle Picnicker Karina, who has a level 14 Piplup. You get 504 Pokédollars for winning.
If you go east past the house, then south down the stairs, you will find a Super Potion.
Go north, and if you go into the house, you can talk to the person near the bed to rest and heal up your pokémon.
If you go outside and go northwest from the house, you can enter Eterna Forest.