A Wooloo goes missing and you enter the mysterious Slumbering Weald to try to rescue it.
Look for Wooloo
When you enter the Slumbering Weald, there will be a cutscene. Go west and you will encounter a wild Skwovet in the tall grass. You don't yet have any pokéballs, so if you do have any wild pokémon encounters, just use your starter pokémon to defeat any pokémon that you encounter.
Talk to Hop on the way and he will heal your pokémon. Go west and you will go through some more grass, where you will encounter a Rookidee. Afterward, you will hear a pokémon and Hop will run up to you. You can talk to Hop again to heal up your pokémon.
Continue on, and you will encounter a wild Skwovet. Keep going, and soon Hop will run past you. Keep going north until there is another cutscene.
You will have an encounter with a mysterious pokémon. You can't run away, and no matter which moves you use on it, the move will have no effect. Keep trying to use moves against it and there will eventually be a cutscene.
Talk to Mum
Go northwest and check on the door to go into your house. Go east toward the kitchen and there will be a cutscene. Your mum will give you 30000 Pokédollars, and 5 pokéballs.
In the menu, you can now use Mystery Gift. Leave the house and go southeast, then follow the main path. You will encounter Hop along the way and there will be a cutscene. Proceed north along Route 1.