Head south over a series of ledges to fight Pokémon Rangers Mikiko and Johan, and pick up the Dive Ball between them. Defeat Black Belt Rocky to clear the south exit to Undella Bay, then cross the bridge to return to the north side. Grab the Full Restore near Battle Girl Tia, and jump the northernmost ledge again. Turn east this time, and go down the stairway to reach the water's edge. Nab the Heart Scale from the bit of dry land, then swim northward. Take the stairway to the lower level.
Go south to the smaller of the two raised platforms. Pick up the Max Repel to the south, then drop the boulder into the hole. Continue east to reach Battle Girl Maki and the larger raised platform. Use Strength to move the first five boulders into position, and pick up the Rare Candy on the way past. Move the sixth boulder and head northwest to return to the first floor.
Head west to find TM06 (Toxic) sitting atop the cliff, then jump the lower ledge near the water. Climb the opposite stairway to find an unusual boulder blocking the east exit. Activate the Colress MCHN to wake the rock, which turns out to be a Crustle. The delicate instrument breaks after the battle. Step outside to reach a secluded part of Route 21's ocean.
Route 21 (east)
The Plasma Frigate
Outside, the Plasma Frigate is anchored at the water's edge. As you approach it, Hugh emerges from Seaside Cave and wonders aloud how to board the ship. Just then, the gangplank falls with a heavy thud, and Marlon disembarks the ship. He still hasn't changed his mind about Team Plasma, but wanted to help the two of you. He leaves, and Hugh runs up onto the ship.
Two Plasma Grunts block the way; defeat one and the pair runs off. Follow Hugh north in search of Zinzolin.
Just inside the North Entrance, you pair up with Hugh to take on a couple of Grunts. He leads with his starter Pokémon at level 50, which is great against the four Poison-type Pokémon unless it happens to be a Serperior. Hand the pair a quick defeat and they hurry off. Before he leaves, Hugh claims that the barrier can be deactivated by either flipping a few switchesB2, or using a passwordW2. Leave this room, and take either the northernB2 or southernW2 stairway to reach the basement.
There are three Grunts here; the first will not attack, but the others will if they detect you. If you need to heal up, you can visit the bed in the northeast room. In the west room, a Grunt will record the entries for Reshiram and Zekrom in your Pokédex. The six rooms that surround the stairwell each have warp panels that aim to disorient intruders. Four of these tiles lead back to the switches inside the North Entrance.
Northwest room, top-left corner
East room, top-left corner
Southwest room, top-left corner
Southeast room, bottom-right corner
With the four switches engaged, the electrified barrier deactivates. Step on the teleporter to warp to the Command Center.
There are three Grunts here; the first will not attack, but the others will if they detect you. If you need to heal up, you can visit the bed in the east room. In the west room, a Grunt will record the entries for Reshiram and Zekrom in your Pokédex. There are five clues needed to learn the password, which changes with every adventure and may contain letters or numbers. Using the password requires the Plasma Card, which can be obtained from the female Plasma Grunt in the center of the dining hall, the west/southwest room.
With the password entered, the electrified barrier deactivates. Step on the teleporter to warp to the Command Center.
Zinzolin is waiting here, and shows off the source of the ship's power, Kyurem. Hugh appears, and joins you in a Multi Battle against Zinzolin and the Plasma Grunt. All but one of their Pokémon are susceptible to Fighting-type attacks, while Weavile is especially vulnerable.
The Giant Chasm is a crater-shaped cave, with a small forest covering the crater floor. The residents of nearby Lacunosa Town fear the monster that is said to hide here. The west side of the cave opens up to Route 23.
Go south from the entrance to encounter a pair of Plasma Grunts. Hugh shows up and attempts to battle them, but a former Plasma member, acting as a spy for Rood, uses his wits to chase them off. Continue south to reach a boulder; use Strength to clear the way, then Surf north to get TM13 (Ice Beam). Head southwest to reach the Route 13 entrance.
Re-enter the cave and turn west. Inspect the nearest rock for a hidden Star Piece, then move the boulder in the southwest corner to reach a Max Repel. A pair of Plasma Grunts blocks the west exit to Route 23 for now. In the northwest corner, a hidden Ultra Ball lies on the west side, while a second Star Piece lies behind a boulder on the north side. Turn east and move the last boulder to find a hidden Ice Gem. Jump the ledge and head southwest to reach the Crater Forest.
Inside the crater, Rood and a pair of Grunts from the old Team Plasma are trying to convince a group of current members that what they are doing is wrong. Hugh breaks up the fight, drawing the Grunts' attention, and drawing the two of you into battle. Rood gives you three Max Revives as thanks for your help. His group will keep the others busy while you and Hugh track down the Shadow Triad aboard the Plasma Frigate. Check the surroundings for a Razor Claw and a Moon Stone, then follow Hugh up onto the mound of ice and into the ship.
Hugh is already holding off a group of Plasma Grunts, leaving you free to advance. The front of the ship has already been cleared, so head to the stern this time.
When you warp into the room where Kyurem is imprisoned, you draw the attention of the nearby Plasma Grunt. He turns out to be the spy that is working for Rood, and informs you of the room's layout and how to proceed. To the south is a maze of pipes; navigating the area requires activating switches that extend and retract these pipes.
There are five clues needed to learn the password, which changes with every adventure and may contain letters or numbers. Using the password requires the Plasma Card, which can be obtained from the female Plasma Grunt on the north side of the maze.
With the password entered, the electrified barrier deactivates. Head north to reach Kyurem.
When you warp into the room where Kyurem is imprisoned, you draw the attention of the nearby Plasma Grunt. He turns out to be the spy that is working for Rood, and informs you of the room's layout and how to proceed. To the south is a maze of pipes; navigating the area requires activating switches that extend and retract these pipes. On the floor below is a series of warp panels which will eventually lead to the four red switches that deactivate the barrier.
Second column from left, near the Plasma Grunt
Northwest corner of the maze
Third column from left, near the female Plasma Grunt
Northeast corner of the maze
With the four switches engaged, the electrified barrier deactivates. Head north to reach Kyurem.
Deactivate the barrier and proceed. Kyurem is stuck in a cage to the north. When you approach it, Zinzolin appears and tries one last time to stop you. His Pokémon have only grown by one level since your last encounter, so the strategy to defeating him is the same.
Ignore Zinzolin's vague threats and proceed. The warp tile to the left is blocked, so take the one to the right to reach the Control Room.
Colress is waiting inside the Control Room. He joined Team Plasma at the request of an old friend, in order to research how to bring out the full power of Pokémon. It does not matter to him which method does the job. One last battle with you will apparently show him which is right. Four of his Pokémon are vulnerable to Fire- and Ground-type attacks, while his Beheeyem fears Ghost- and Dark-type moves.
Defeated, Colress recognizes your strengths. Which method is better, Team Plasma's science or the bond between Trainers and Pokémon? He suggests that you find out for yourself by taking the warp panel on the west side of Kyurem's prison.
Meet Ghetsis, the man who has been behind Team Plasma's schemes from the beginning. He is furious that Colress lost to you, but his ambitious plans are still in motion. He intends to use Kyurem to freeze Unova and force people and Pokémon to submit to his reign. Before exiting the ship, he summons the Shadow Triad to take care of you. The Shadows only attack when challenged, so you will have a chance to heal your Pokémon between battles.
Defeated, the Shadow Triad finally returns the Pokémon that belonged to Hugh's sister. Purrloin has evolved into Liepard and only listens to the Triad, but Hugh finally got what he wanted. Leave the ship, descend the mountain of ice, and enter the cave to the north.
Proceed to the deepest part of the cave to find Ghetsis. He proclaims that he will freeze the region from here, where Kyurem's power is strongest. He summons the dragon and commands it to attack you with Glaciate, but something interferes. It's N, flying in on ZekromB2 or ReshiramW2. His dragon told him that Kyurem is suffering, and he is here to help. But Ghetsis planned on that, and uses the DNA Splicers to fuse Kyurem with the other dragon, resulting in Black KyuremB2 or White KyuremW2. Disrupting signals from Ghetsis' cane prevents capture, so there is no choice but to defeat the new dragon, which is vulnerable to Dragon-, Fighting-, Rock-, and Steel-type attacks.
Utterly defeated, Ghetsis appears to have lost his senses, and the Shadow Triad takes the old man away. Without a leader, Team Plasma is left in ruin. N suggests visiting the Pokémon League before climbing onto his dragon and flying off. Hugh enters to make sure that Team Plasma is truly finished, and after a few words of encouragement, informs you that Route 23 can be reached from the west side of the outer cave.