After you go east through Mount Coronet and Route 208, you reach Hearthome City.
Meet Keira
When you go east into Hearthome City, there will be a cutscene where you meet Keira.
Get a Pokémon Egg
In the southeast part of town, talk to a hiker to get a pokémon egg. You will need to make room in your party for it. If you keep it in your party, it will eventually hatch.
Get a Poffin Case
To the north, you find the Pokémon Fan Club building. Go inside and talk to the person in the corner, and if your lead pokémon has high friendliness, you will get a Ribbon.
Talk to the person on the couch to get a Poffin Case.
Super Contest Shows
Talk to the purple-haired person outside of the Contest Hall and there will be a cutscene.
In the Contest Hall, during a cutscene, Keira will give you a Sticker, and your Mom will give you some clothes to wear during Super Contest Shows.
Talk to the person at the middle counter. If you don't have a Poffin Case, they will recommend that you get one. If you do have a Poffin Case, they will give you a Mild Poffin.
Visit the Super Contest Shows page for more information on how to participate in Super Contest Shows.
Get a Shell Bell
In the building east of the Pokémon Fan Club, go up the elevator and talk to the person at the table to get a Shell Bell. If you give it to a pokémon to hold, the pokémon will gain a small amount of HP when they do damage in battle.
Poffin House
West of the Hearthome City Poké Mart, you find the Poffin House. You can cook Poffins by talking to the person near the blender.
Hidden Tiny Mushroom
If you go to the northwest corner of Hearthome City, you can walk between the fence and the trees. At the end of the path, there is a hidden Tiny Mushroom.
Amity Square
You can go north from Hearthome City to find Amity Square. After your first visit to Amity Square, you can have any pokémon follow you while not in Amity Square.
Battle Your Friend
After you have visited the Contest Hall, go south in Hearthome City until your friend runs up to you and challenges you to a battle. He has a level 19 Starly, a level 20 Buizel, a level 20 Ponyta, and a level 21 Monferno if you chose Turtwig, a level 21 Prinplup if you chose Chimchar, or a level 21 Grotle if you chose Piplup. You get 2352 Pokédollars for winning.
Go Southeast
Go southeast in Hearthome City, and you will now be able to go through the gate near the Hiker who gave you the egg. You will reach Route 209.