The Valley Windworks is a large wind farm situated in a windy valley close to Mt. Coronet, so as to generate as much electricity as possible. It is located just off Route 205, a short walk east from Floaroma Town. In the area, there are nine tall wind turbines which generate energy that is in turn processed by the power plant in the center of the area. West of the plant is a large patch of tall grass, where many wild Electric-type Pokémon live. To the north of the power plant building is a river which runs onto Route 205; a Max Elixir and TM24 (Thunderbolt) can be found by surfing on it.
Inside of the power plant building there are many machines which process the electricity produced and send it out to the cities and towns of the Sinnoh region, while the plant owner and his daughter remain to explain how the plant works and about Drifloon, respectively.
Every Friday, one Drifloon will appear in the middle of the Valley Windworks. It will only appear after Team Galactic has been vanquished, at level 22DP or level 15Pt. If it is not battled and captured or fainted by the end of Friday, it will disappear until the following week.
Team Galactic takeover
During the course of the game, Team Galactic will take over the Valley Windworks, kidnapping the worker and kicking his daughter out. Their plan is to steal energy to help Cyrus to achieve his plan to create a new world. One Galactic Grunt will be standing guard in front of the door to the power plant. When defeated, he will run inside and lock the door, which will not open unless unlocked by the Works Key, one of which is held by a Grunt in Floaroma Meadow. In order to rescue the plant worker, Mars must be defeated. In Pokémon Platinum, Charon is also here but the player won't have to defeat him. During this encounter, it is revealed that he joined the team after Mars. It is also here where the player discovers that Charon is in fact, one of the four Commanders.
In Gone With the Windworks!, Lyra's Marill wandered inside the Valley Windworks, and Ash and his friends had to go inside to retrieve it. However, due to the power going out, they were temporarily trapped inside. Benjamin guards this location with his multiple Magnemite and many security cameras, but he is generally asleep.
In the manga
Valley Windworks in Pokémon Adventures
In the Pokémon Adventures manga
The Valley Windworks appeared in Honey for Combee and Belligerent Bronzor, where Diamond, Pearl, and Platinum went to the site to help find a little girl's father, whose Drifloon had returned from the Valley Windworks injured, carrying his tattered lab coat. The three Pokédex holders discovered that Mars, one of Team Galactic's Commanders, was holding the little girl's father as hostage to make him generate electricity for her to steal for the Galactic Bomb, using her Bronzor's Sandstorm to speed up the process. Although Mars got away with the electricity stored within her Electivire and the Pokédex holders almost got buried in Sandstorm's sand, everybody managed to survive the incident.
In Platinum, after defeating Mars, this message will be displayed on both computer screens:
"The bringer of wars... Your target is the energy of the power plant. The bringer of contentment... Your target is the Pokémon statue of Eterna City. The bringer of aging... Your target is the Pokémon that sleeps on today. The dream energy. Team Galactic."
This message likely refers to Gustav Holst's orchestral suite The Planets. The epithet of each commander corresponds to the first, fourth, and fifth movements of the suite, respectively: Mars, the Bringer of War, Jupiter, the Bringer of Jollity, and Saturn, the Bringer of Old Age. The message shows where each of Team Galactic's three commanders is stationed: Mars was at Valley Windworks gathering power, Jupiter may have been the one to deface the Eterna Pokémon Statue (as she is in the city when the player arrives) and Saturn tries to capture the sleeping Azelf.
The message is replaced at some point in the game, most likely after the events at the Spear Pillar.
In Diamond and Pearl, if Dialga or Palkia is battled on a Friday, the overworld sprite of Drifloon can be seen when the cutscene preceding the battle briefly shows Valley Windworks.