When you walk downstairs from your room, you meet your mom's "twin". The mystery guest takes off the disguise and introduces himself by his code name, Looker, a member of the International Police. Thanks to you and the Gym Leaders, Team Plasma has fallen, but the Seven Sages are still at large. He asks you to help track them down, and gives you an item which has nothing to do with your search, the Super Rod, as thanks. Fish wherever you can to find not only stronger Pokémon, but also species foreign to the region.
Outside, Bianca and Cheren are waiting for you. Bianca apologizes for not alerting the Striaton Gym Leaders in time, and Cheren tells you that Ghetsis escaped from custody thanks to the Shadow Triad. He asks what everyone plans to do now, and Bianca says that she's headed to the settlement east of Nimbasa City. As the three of you discuss your plans, Cedric Juniper leaves the lab. He says that he just acquired new data from an acquaintance, and upgrades everyone's Pokédex with the National Mode! Everyone goes their separate ways, leaving you free to start hunting for the sages.
To find the nearest sage, surf west from Route 1, and continue west to Route 18. Rood is on the beach on the island's southwest side, staring out to sea. He tells you about N and Ghetsis, then gives you TM32 (Double Team). Looker then arrives to take him into custody.
The obstacles are now gone, so you can now enter the basement. Some of the Trainers underground will run when you approach them. Wait around the corner, and talk to them from the side to battle them. Fight your way to the southwest part of the basement to find a TwistedSpoon, then climb up the stairs in the southeast.
Pick up the Revive to the west, then go south to find the next of the sages. Gorm jumps out from behind the wall, and tells you about Team Plasma and N's Castle. He gives you TM75 (Swords Dance) before Looker shows up to arrest him. Head west to find a Hyper Potion, move the boulder to create a shortcut, and go back down to the basement to grab TM85 (Dream Eater) from the north corner. On Fridays only, a Musharna will appear in the eastern patch of grass. This is the only Musharna that can have the Hidden AbilityTelepathy, so make sure to catch it!
Visit the Game Freak building and take the elevator to the 22nd floor. If you talk to the Sound Designer, the background music will change to that of Team Rocket, the villains of HeartGold and SoulSilver.
The Regional Diploma
Talk to the Game Director here when you complete the Unova Pokédex, and he will reward you with a Diploma. It will then be hung on the wall of your bedroom in Nuvema Town. He will give you a second Diploma for completing the National Pokédex, as well.
Across from the Sound Designer is a character named Morimoto, who will battle you once per day after you defeat the Elite Four. He represents a real person that helped create most of the Pokémon video games.
Trainers can board the Royal Unova in the evening. If you defeat a certain number of Trainers on board, you can get a prize. The challenge and prize change depending on the day of the week. Talk to the crew to get hints on where the Trainers are. You can climb the stairs to the deck to view the sun setting. Whistles blow several times, and eventually the ship will return to port. Beat the Trainers within the time limit to earn your reward!
After entering the castle itself, continue along until you reach B5F, the room where you and Alder confronted Ghetsis. The sand has piled up so that you can reach the door on the east side of the room. In the hallway beyond, a Team Plasma Grunt runs off when you get too close. Climb down the staircase to enter a maze of underground chambers, where the same Grunt attacks you. Go west to the opposite bi-level hallway, and scale the Relic Castle Tower to the top floor to get TM26 (Earthquake). Climb back down the tower and travel southeast through the maze of chambers; you'll eventually meet Ryoku of the Seven Sages. He had been planning to catch the Volcarona in the next room for Ghetsis, but abandons his plan. He gives you TM04 (Calm Mind), then Looker takes him into custody.
You can now take the Battle Test at the Battle Institute. The test assigns challengers a rank based on the results of battling five Trainers. Aim for a high rank by challenging it with your best-trained Pokémon.
Big Stadium and Small Court
During practice at the Big Stadium and Small Court, the Trainers here are looking to battle. Having completed the main story, there are not only more opponents to fight, but the levels of their Pokémon are a lot higher as well. Some will give you valuable items after you defeat them, like a Max Revive or PP Max. Visit every day to get lots of items!