After you obtain all eight Gym Badges, all 5 Titan Badges, and all 5 Team Star Badges, Arven asks you to meet him near Medali.

How to Start the Way Home

Before you can proceed, you need to get all eight Gym Badges and pass the Champion Assessment, you need to get all five Titan Badges and complete the events that happen after that, and you need to get all five Team Star Badges and complete the events that happen after that.

After you complete both, you will get a call from Arven, who will add a destination to your map, near Medali. Go to Medali, then go southeast to the destination on the map.

Near Medali

After the cutscene, go down the elevator as instructed, then after the cutscene, go forward approach Arven. If you are ready, say Yes, and there will be a cutscene.

Area Zero

In this area, you can't ride Koraidon/Miraidon. The map will not show you any details of the area. Make your way clockwise to go downward, and there will be some dialogue as you go. You can use the Flying Taxi to leave the area at any time. Note that if you fall, you will automatically be sent back up to where you were.

Research Station No. 1

When you approach the first research station, you and Nemona will battle a level 62 Glimmora. Nemona has a level 65 Lycanroc.

Afterward, enter the research station and there will be a cutscene. After that, check on the computer to disable the lock. You can use the bed here to rest if you wish. There are a couple of books here that you can read. There is also a teleporter near the exit that you can stand in to teleport back to the Zero Gate if you wish.

When you are ready, go back outside and make your way downward. Approach the second research station when you find it.

Research Station No. 2

If you are playing Pokémon Scarlet, the second research station is guarded by a level 62 Scream Tail. If you are playing Pokémon Violet, the second research station is guarded by a level 62 Iron Bundle. You battle it along with Penny, who has a level 62 Umbreon.

Afterward, enter the research station and there will be a cutscene. If you are playing Pokémon Scarlet, you get the Scarlet Book; if you are playing Pokémon Violet, you get the Violet Book. You can go to the Key Items section of the X menu to read it.

After the cutscene, check on the computer to disable the lock. You can use the bed here to rest if you wish. There are a couple of books here that you can read. There is also a teleporter near the exit that you can stand in to teleport back to the Zero Gate or Research Station No. 1 if you wish.

When you are ready, go back outside and make your way downward. Approach the third research station when you find it.

Research Station No. 3

If you are playing Pokémon Scarlet, the second research station is guarded by a level 62 Great Tusk. If you are playing Pokémon Violet, the second research station is guarded by a level 62 Iron Treads. You battle it along with Arven, who has his level 63 Mabosstiff. Afterward, enter the research station and there will be a cutscene.

After the cutscene, check on the computer to disable the lock. You can use the bed here to rest if you wish. There are a couple of books here that you can read. There is also a teleporter near the exit that you can stand in to teleport back to the Zero Gate, Research Station No. 1, or Research Station No. 2 if you wish.

When you are ready, go back outside and enter the cave straight ahead. In this cave, you will begin to encounter Pokémon such as the Quaking Earth Titan and the other strange Pokémon that you encountered earlier, as well as others. Feel free to try to catch them.

As you proceed farther, there will be a cutscene. After that, keep making your way downward. Approach the fourth research station when you find it.

Research Station No. 4

In the research station, there will be a cutscene. You can use the bed here to rest if you wish. There are a couple of books here that you can read. There is also a teleporter near the exit that you can stand in to teleport back to the Zero Gate, Research Station No. 1, Research Station No. 2, or Research Station No. 3 if you wish.

Check on the computer, then go outside, and keep making your way downward. Approach the yellow, hexagonal door with a ramp leading up to it, and there will be a cutscene.

If you are ready, check on the computer next to the ramp and say Yes, then during the cutscene, say Yes to the question.

If you are playing Pokémon Scarlet, you and Nemona will battle a level 64 Great Tusk. If you are playing Pokémon Violet, you and Nemona will battle a level 64 Iron Treads. Nemona has a level 65 Lycanroc and a level 65 Pawmot.

After that, if you are playing Pokémon Scarlet, you and Penny will battle a level 64 Brute Bonnet. If you are playing Pokémon Violet, you and Penny will battle a level 64 Iron Hands. Penny has a level 62 Umbreon.

After that, if you are playing Pokémon Scarlet, you and Arven will battle a level 64 Flutter Mane. If you are playing Pokémon Violet, you and Arven will battle a level 64 Iron Jugulis. Arven has his level 63 Mabosstiff.

Enter the Zero Lab

If you are ready, go up the ramp and enter the Zero Lab. Go forward through the pipe, then go to the right to enter the lab. Make your way farther into the lab and there will be a cutscene. Afterward, take the item to get a Booster Energy, then talk to the professor.

After the cutscene, talk to the professor again. If you are ready to proceed, place the book on the pedestal as instructed. If you need to prepare, you can approach the elevator door to return to the Zero Lab, then go back into the broken pipe and go to the end to return to Area Zero. From there, you can take a Flying Taxi to wherever you wish.

Battle the Professor

If you are playing Pokémon Scarlet, the professor has a level 66 Slither Wing, a level 66 Scream Tail, a level 66 Brute Bonnet, a level 66 Flutter Mane, a level 66 Sandy Shocks, and a level 67 Roaring Moon.

If you are playing Pokémon Violet, the professor has a level 66 Iron Moth, a level 66 Iron Bundle, a level 66 Iron Hands, a level 66 Iron Jugulis, a level 66 Iron Thorns, and a level 67 Iron Valiant.

Afterward

After that battle, there will be a cutscene. In the battle that follows, open the list of Pokémon and select Koraidon/Miraidon. If battling with Koraidon, use Collision Course. If battling with Miraidon, use Electro Drift. When one of your friends says "This looks like it could be bad! Hang in there!", use Endure. When they say that your Tera Orb is glowing, Terastallize and attack with Tera Blast.

Congratulations! You won! After the end credits, you can begin the Post-Game.