Route 6 is a road surrounded by rich nature. The path crosses back and forth over the river and continues on past the Season Research Lab. Chargestone Cave lies further north, and Mistralton Cave stands to the east.
Cheren is continuing with his investigation outside the Season Research Lab. The data he has collected shows sudden drops in temperature near Lacunosa Town, Castelia City, and Driftveil City, with some areas dropping as low as -58°F. He gives you HM03 (Surf) to help you travel around and assist the investigation.
Season Research Lab
The Scientists at the Season Research Lab are conducting research on Deerling, and the reason it changes forms with the season. If you have an open party slot, one of the Scientists will ask you to raise a rare Deerling that they found, one with its hidden Serene Grace ability.
When you have a traveling partner that has a move or ability that can change the weather, the Parasol Lady will describe the respective condition in detail.
A Legendary Pokémon Appears
When you reach the westernmost bridge, the legendary Cobalion jumps down from the nearby cliff and lands directly in front of you. However, it runs off as quickly as it appeared. Immediately after, Rood of the Seven Sages appears and claims that Cobalion will be a great asset if you can befriend it.
East of the bridge is a second building. Speak to the woman inside to have her heal your Pokémon. Surf east along the river from here to reach Mistralton Cave.
The darkness makes it difficult to see, so use Flash to light the way. Go south and push the boulder onto the hole in the floor. Follow the tunnel past Hiker Shelby and move the second boulder into place. The southeast corner connects to Clay Tunnel, which is still under construction. Head north to get a Dusk Ball in the northeast corner and a Yellow Shard north of the entrance. Move the third boulder into place to create a shortcut, then go south to reach the stairs to 2F.
Head southeast and push the next boulder into place. Walk east along the rock platform, then loop around to the southwest to reach a Hyper Potion. Head up along the east wall to the northeast corner, then walk west along the rock platform to get a Blue Shard. Backtrack to Ace Trainer Belle, push the next two boulders into place, and climb the stairs to the Guidance Chamber.
Go east then north to find TM80 (Rock Slide) in the northeast corner. Turn around, climb onto the southeast rock platform, grab the Escape Rope, and continue north. Go down the stairway, turn south, and move the next boulder into position. To the west is an old man who has been searching for Cobalion for decades. Long ago, Cobalion, Terrakion, and Virizion rescued Pokémon from a fire caused by a war between humans. From that point on, the three have refused to associate with people. The old man wonders aloud if Cobalion's hatred has lessened...
When you're done in Mistralton Cave, continue north on Route 6 to reach Chargestone Cave.
Go north to meet Bianca, who tells you that the floating stones can be moved out of the way. North of her is the first floating stone; push it to the left so that it sticks to the blue boulder. Pick up the Full Heal, and push the next stone to the right. Turn east to get a Max Repel to the south of Scientist Ronald, then backtrack and go north. Check the ledge north of Guitarist Anna for a hidden Yellow Shard, then grab the Hyper Potion in the alcove to the east. Move the next two floating stones and continue eastward. At the T-intersection, go north for a hidden Hyper Potion before heading south to the bridge.
Crossing the bridge, you hear someone's voice. The voice says, "I have to go in order to save Pokémon and protect the very friend that I have to stop!" The person leaves before you have a chance to learn their identity.
Fight Ace Trainer Corky in a Triple Battle, then loop around to the west to get a Magnet. Climb down the stairs to B1F.
Head west to meet the Nugget Man and the Nugget Boy, who give you both a Nugget and a Big Nugget. Continue west and climb the stairs; talk to the Lady to receive a new Funfest Mission, Find Mysterious Ores!B2 or Find Shining Ores!W2. Go back downstairs and head north. Check the passage to the north of the Nugget Man and the Nugget Boy to find a hidden Ultra Ball, and pick up the Iron to the east. Defeat Doctor Kit to have him heal your team, and continue north. Pass by Scientist Lumi, and navigate around the blue boulders to the west to get a Revive. Here you meet Bianca again, who is researching the local Tynamo at Professor Juniper's request. Go down the western stairs to B2F.
Go south of Guitarist Beverly to reach an Escape Rope. Grab the Thunderstone to the north of Ace Trainer Shaye, then head south. Fight Ace Trainer Vicki in a Rotation Battle, then climb down to the lower level. Pick up the Metal Coat, then check the dead-end path for a hidden Electric Gem. Backtrack to the stairs to return to B1F.
Walk east past Bianca and climb up the stairs to 1F.
Head south to reach a Carbos near Hiker Otto, then go east to reach the exit to Mistralton City. Your sixth Gym battle awaits!