If you get the Yureyu Key from the Byxbysion Wall (you can get it when you obtain the green crystal key which is located in Iolia Valley, and then use it at Tanzan Mountain near the entrance of Route 1), you can use the the key to open both locked doors.
On the right there will be a two items; a Magnet and TM 95 Snarl.
On the left You can evolve Nosepass, Magneton, and Charjabug since this room has a special magnetic field.
A lady in one of the houses in Lapis claims that her child has gone missing and requests the player to help her find him. The child can be found outside the Abandoned Power Plant in Windy Weather, intimidated by a Drifloon. After defeating/capturing the wild Pokémon, the child is next found in the Jasper Ward, cornered by a Pokémon Swarm. Defeat the Pokémon Swarm and the child will reach home safely. Talk to the lady after rescuing her child and she will reward the player a Department Store Sticker.
During windy days, a boy and a Drifloon will be found here. Deal with Drifloon and the boy will run to Jasper Ward.
On the left there will be multiple Electrodes LV85. Defeat each one and interact with the computer screen. Rotom will appear as a special encounter that you can catch at LV65. If you check the summary of Rotom, you can see it belonged to Shade.
A telecommunicator is located in the entrance of the Power Plant.
Go around to the 4 different monitors in the plant and turn them off and witness events that become familiar as the game progresses.