After passing through Route 1, you will find Bianca and Cheren waiting for you near the entrance to Accumula Town, and after talking about how many pokémon you caught, you'll all take your first step on your Pokémon adventure together.
Once in Accumula town, you should head to the Pokémon Center, where Professor Juniper is waiting for you. She will show you around the facility, asking you to heal up your pokémon at the desk. She will then show you the PC, and finally the PokéMart, which is built into the Pokémon Centers, unlike in previous games where they were in a separate building. Much more convenient!
Professor Juniper will ask you to head on to the next town and meet with her inventor friend, Fennel. She will then depart from the Pokémon Center.
Go outside and some people will be walking toward the plaza, where someone is giving a speech. Cheren is in the crowd. Go up and talk to him, and the speech will commence.
Ghetsis gives a speech that questions the true nature of the relationship between humans and pokémon. Are they really friendly companions and partners, or are humans enslaving the pokémon against their will? Ghetsis says that it's the latter, and that people should liberate their pokémon. But he seems to be leading Team Plasma, so he can't be up to any good….
After the crowd disperses, a mysterious man by the name of N stays behind. He claims to be able to hear the words of your pokémon, and he challenges you to a battle in order to listen to your pokémon more.
This battle is not too difficult. There shouldn't be any surprises. Just keep your pokémon healed up.
After the battle, N will leave, but it sounds like you'll meet again in the future. Cheren will continue on his way, too.
After the encounter with N, you can explore the town. There's no Gym here, but there might be some people here who give you items. There is also a house where a piano player and drummer will add their accompaniment to the town music.
When you're ready, head west to go through a building. You can see an electronic sign with messages about Striaton City, which is your next destination.