Ahh, blissful academia. After a long walk you've arrived at the Academy, your new home away from home. If you're playing Pokémon Scarlet it will be called Naranja Academy, and everything will be red-themed. If you're playing Pokémon Violet it will be called Uva Academy, and everything will be purple-themed.
(I'm not currently sure if there are any other differences between the Academies beyond the aesthetics. There's definitely a different NPC in each one, but they serve the same purpose, so...)
The grounds aren't that interesting, so head inside the Academy's main doors. After a conversation with Clavell you'll head to your first class, where you'll meet Mr. Jacq, a teacher who appears to have permanent bed-head. Chatting with the class will unlock classes at the Academy, which you'll get to shortly. Once Jacq is done talking you can leave the classroom and explore the Academy.
The Academy has a variety of places to check, though for now you're limited to Classroom 1-A, the Cafeteria, and the Staff Room.
Cafeteria
Head to the Cafeteria first and you'll find a vendor who will sell you Sandwiches. You'll also find Arven, the gent who battled you at the lighthouse on Poco Path. He'll outline his dream - gathering rare, exotic herbs - and admit that he's not cut out to make it happen, as the herbs he wants are guarded by Titan Pokémon. He doesn't have the strength to fight them...
... but you, eventually, will. Arven will provide you with the locations of five Titan Pokémon, found throughout Paldea, and you'll need to track them down and defeat them. This unlocks the Path of Legends, one of the game's three main quests. Arven will also give you some Stardust for your trouble.
On the way out of the Cassiopeia your Rotom Phone will spring to life on its own, and a mystery caller named Cassiopeia will speak. Cassiopeia is concerned with the antics of Team Star, and needs an ally to take them down. Agree and you'll become an ally in the war. More on this later.
Entrance Hall and Classes
Leave the Cafeteria and you'll be sent out to the Entrance Hall of the Academy. Consisting of three floors, theEntrance Hall also serves as a library. Check the conspicuous green books jutting out of the many bookcases and you'll learn more about the Paldea Region, as well as discover hints towards future quests you might undertake. Of particular note is the colored book on a shelf on the ground floor, which contains a great deal of information on a variety of topics.
Of more interest right now, though, is the front desk on the ground floor. The receptionist here will allow you to take Classes. During Classes you'll be asked a variety of questions, and answering correctly will build your relationship with the teachers. Gain their trust and you'll earn some fancy rewards. Along with classes you'll have to take Mid-Term and Final Exams that will put your knowledge of Pokémon to the test. You'll unlock more Classes, and more levels of Classes, as you proceed through the gyms of Paldea. We'll take a more in-depth look at Classes in another article.
Throughout the Entrance Hall you'll find doors with gates in front. These will take you to other sections of the Academy. Use one of them to reach your next destination, the Staff Room.
Staff Room / Director's Office
Check out the Staff Room and you'll find Nemona speaking to... someone. Once they leave Nemona will explain the Champion system in place at the Academy, and how you can become one. The path is pretty familiar to players of previous Pokémon games: Beat eight gym leaders located throughout Paldea and complete a Champion Assessment. Learning of this will put you on the Victory Road quest path.
Once Nemona leaves you'll get buzzed to the Director's Office. Here you'll (remotely) meet either Professor Sada (Pokémon Scarlet) or Professor Turo (Pokémon Violet). The Professor will tell you a bit more about the Pokémon that has been helping you, and will ask you to continue to care for it going forward. Once you're done talking Nemona will show up...
Your Dorm Room / Schoolyard
... and whisk you off to Your Dorm Room. You can use this room to rest up and fully restore your Pokémon. You'll probably notice that the shelves are conspicuously bare, a sure sign that you can fill them up with trinkets. More on that once you procure said trinkets. For now, though, you'd best have a snooze.
The next day Nemona will fetch you again, and take you down to the Schoolyard. Here Clavell will announce the school's next major activity - A Treasure Hunt - and tell everyone to seek their own particular treasure. This more or less marks the 'beginning' of the game, and soon you'll be free to explore the world of Paldea at your leisure.
First, though, head back into the Academy's Entrance Hall. If you check any of the door gates you'll see that you can now access the remainder of the Academy. Let's have a quick look around at the remaining rooms. (And no, this isn't mandatory. There's very little to see in any of them at the moment.)
- School Store - Sells a variety of basic items. More or less a Poké Mart inside the Academy.
- Biology Class - Where you'll take Biology Classes. Jacq is found here.
- Art Room - Where you'll take Art Classes. It's run by Hassel.
- Home Ec Room - Where you'll take Home Ec Classes. It's run by Saguaro.
- Nurse's Office - A place for convalescence where you can rest up, if you'd rather not use your dorm room. It's run by Miriam.
- Schoolyard - A play and training yard. It's the only place on the Academy grounds where you can let your Pokémon run around.
- Classroom 1-D - Penny's homeroom. (The girl with the Eevee sweater.) You can find her here if you need her, though she's not here right now.
- Classroom 2-G - Arven's homeroom. He also isn't there right now.
There's not a ton to see in any of these locations right now, though if you want to spend time building relationships with your classmates and the teachers you'll wind up jumping between the rooms a lot.
That's all for the Academy. Head back towards Mesagoza you'll have a conversation with Nemona and Arven about your next destination. You'll also get a call from Cassiopeia, who will task you with tracking down, and trouncing, the five bases of Team Star. This will put you on the Starfall Street path, giving you three options for progressing the main game. You can tackle Path of Legends, Victory Road, and Starfall Street as you see fit, and each path will give you more time with its respective NPC.
Once the conversation is done you'll receive one final boon: Your mystery Pokémon (Koraidon or Miraidon) will transform into a vehicle. You can hereafter hop on the Pokémon's back and ride it around for more speed. Nice. Your mount can also jump, allowing you to reach heights you can't on foot.
The world is now your oyster, and you can travel Paldea however you like. Before you leave Mesagoza, however, have a look down the stairs to the south of the Academy. There's a woman here who will look into your 'past lives' and give you Rotom Phone Cases based on your experiences. (In other words, you'll receive Cases if you have saves from previous Pokémon games on your Switch.)
That's that. Time to set out on an adventure. From this point on the guide will be divided into three sections, one for each Treasure Hunt, and it will be up to you to decide how - and when - you tackle each. Pull up your map to see where they want you to go next. Good luck!