After you make your way through South Province (Area One), you reach the town of Los Platos.
When you first enter Los Platos and approach the Pokémon Center, Nemona will call you over and there will be a cutscene. You will get 5000 LP (League Points), and many Pokémon materials.
Nemona tells you about "Let's Go" mode, where you press R to send out your lead Pokémon, who will automatically battle nearby Pokémon and pick up nearby items. Your Pokémon may lose HP during Let's Go mode, so be sure to heal it up if needed.
Use the Pokémon Center
At the Pokémon Center, talk to the person at the red counter to heal up your Pokémon. You can also ask for help figuring out where you are supposed to go, or register your birthday. If you register your birthday, the first Pokémon Center that you visit that day will celebrate. In addition, wild Pokémon have a small chance of having a special birthday mark (select a Pokémon and choose Check Summary, then use the directional pad to go to the Memories tab and see if a Pokémon has any marks).
At the blue counter, you can exchange Pokédollars or League Points to purchase items.
At the green counter, you can use Pokémon materials to create new TMs. You can also use the green counter to convert materials into LP. Don't convert Gimmighoul Coins into LP, though. You might want to hold onto them for now.
The Union Circle is a yellow circle that you can stand on and check on the computer there to form a group or join a group. This can be a local group for nearby players, or it can be an online group if you have a subscription to Nintendo Switch Online. You can also access Union Circle from the Poké Portal in the X menu, as explained in the next section.
In the X menu, you can now choose Poké Portal to access the online features of the game, such as Trades, Mystery Gift, and so on. You can use the Union Circle feature from here, so you don't have to go to a Pokémon Center to use it. You can connect to the Internet by pressing L while in the Poké Portal menu.
Map of Los Platos and Northwestern South Province (Area One)
Explore the Area
In town, you find an ice cream cart called Sugar-N-Ice where you can purchase ice cream, which will give you Meal Powers. These powers have different effects, such as helping out in battle, boosting Pokémon catch rates, increasing Exp earned, and more. The Adventure Guide in your Key Items explains what each Meal Power does.
South of the two houses west of the Pokémon Center, you will find an Antidote. West of that, just past the boundary of the town, you can find a Potion, an Exp. Candy XS, and TM041 Stored Power.
There is a Paralyze Heal behind the houses in the center of the town.
In the northwest part of town, behind some benches near a pond, you find TM085 Rest.
West of town, you find an Antidote and a Poké Ball, and west of that, on a ledge, there is a Net Ball.
West of the town's pond, there is a sign, and behind it, you will find another Gimmighoul that you can talk to to get a Gimmighoul Coin.
Near that, you can battle Pere the Student, who has a level 4 Azurill and a level 5 Houndour. You get 160 Pokédollars for winning.
On the hill west of town, south of a pond, there is an Ether. Near the south edge of the pond, you find a TM032 Swift.
On the path west of town, north of the sign that had a Gimmighoul behind it, you can go north and talk to the trainer to battle Ruben the Janitor, who has a level 5 Gulpin. You get 460 Pokédollars for winning.
Near Ruben, there is an Aspear Berry.
On the ledge that overlooks the pond in the town, there is an X Sp. Def.
Northeast of the town, there is a narrow passageway that leads to a dead end, where you find a Full Heal, TM031 Metal Claw, and a Revive.
Along the northeast path from the town, you can talk to the trainer to battle Carlota the Student, who has a level 5 Bounsweet. You get 220 Pokédollars for winning.
Near the pond north of Carlota, you will find a Burn Heal. East of the pond, you find another TM032 Swift.
North of Carlota, talk to the trainer to battle Youngster Luka, who has a level 5 Chewtle. You get 220 Pokédollars for winning.
If you keep following this path northward, you eventually reach another Pokémon Center. You can go there to add it as a Flying Taxi destination.
You can talk to the person with the yellow speech bubble to the left of the Pokémon Center, and if you have defeated at least four trainers in South Province (Area One), he gives you TM082 Thunder Wave.
You can optionally go east from that Pokémon Center and talk to the trainer to battle Alberto the Worker, who has a level 7 Shinx. You get 644 Pokédollars for winning.
If you go through the gap in the wall north of the northern Pokémon Center, then go a long way east, you will find a Luxury Ball.
West of the northern Pokémon Center, you can talk to the trainer to battle Iker the Courier, who has a level 6 Rookidee. You get 552 Pokédollars for winning.
There is a pond south of Iker, and if you go west from it, you find an Exp. Candy XS.
If you go west from the northern Pokémon Center while staying along the south side of the stone wall, you can talk to a trainer that you find there, and you will battle Hiker Paula, who has a level 7 Slakoth. You get 420 Pokédollars for winning.
On the ledge south of Paula, there is a Super Potion.
When you are ready to move on, approach the gate to Mesagoza City. There will be a cutscene, and Nemona will challenge you to a battle. Your Pokémon will be healed up for free before the battle starts.
Nemona has a level 8 starter pokémon (Quaxly if you chose Sprigatito, Sprigatito if you chose Fuecoco, Fuecoco if you chose Quaxly) and a level 9 Pawmi, which she will Terastallize. You get 540 Pokédollars for winning. You also get 3 Revives.
Afterward, you go north through the wooden gate and explore Mesagoza.