Upon entering Oldale town, you will be approached by a supremely kindhearted clerk from the Poké Mart. He will tell you about the Poké Mart and give you Potions (x10). He will also show you where the Pokémon Center is.
The Poké Mart does not sell Pokeballs for now and you cannot leave the town by heading to the left as a guy will block your passage.
Go to the north to meet up with your rival.
Head north and you will see your rival studying Pokémon. He will challenge you to your first Pokémon battle. He will use the starter that your Pokémon is weak against.
Pokémon Trainer Brendan/May(Prize Money: P200)
Pokémon:
After the battle, he will tell you to head back to the lab. Follow him back to littleroot Town.
Enter the lab and Professor Birch will give you your Pokédex and your rival will give you Poké Balls (x10). You may now transfer your Pokémon from your Pokébank, if you have any. If you also have completed the special demo, you can now transfer Glalie and other items via Pokemon Link.
Additional Notes:
Leave the lab and try to exit the town. Your mom will see you off. Go to route 101 and your rival will upgrade your PokéNav. He will add the DexNav function. You can access this function by pressing the Pikachu icon on your lower screen.
Keep going north and your rival will show you how to catch Pokémon from rustling grass. Save if you want just in case you accidentally defeat it. Sneak up on the Pokémon by walking towards it slowly. This Poochyena has a rare move: either Ice Fang. Thunder Fang or Fire Fang. It is highly recommended to catch it.
After the battle, head back to Oldale Town.
Poké Balls are now available at the Poké Mart. You can buy Antidotes as well.
Head to the west of the town. The guy there will no longer be blocking the path and you may proceed to Route 102.