Valley Windworks is found in Pokemon Diamond, Pokemon Pearl, and Pokemon Platinum to the southeast of Route 205. It is surrounded by windmills which are used to generate electricity. The player battles one of the three Team Galactic Commanders there. After beating him and his grunts, and saving a scientist inside, the player learns about a mysterious balloon Pokemon that appears in front of Valley Windworks on Fridays. You can battle or catch this Pokemon when you find it. This Pokemon is of course Drifloon. It will be Level 22 when you face it. It is the first Drifloon you can catch in any Pokemon game.
Why did this Drifloon choose Valley Windworks to appear at, and why did it choose Fridays?
First of all, it is important to realize that Drifloon shares similarities with a balloon, and balloons float, or in Drifloon's case, balloons drift through the wind. Drifloon actually inflates and deflates itself to move through the wind. It makes sense that it'd be attracted to somewhere with lots of wind. Where better than Valley Windworks? Hell, wind is in the name. Since wind energy is used to turn the turbine of the windmills to generate electricity, it's safe to assume that there is plenty of wind at Valley Windworks for this Drifloon, and plenty of electricity, which brings me to my next point.
Drifloon is a ghost-type Pokemon, and is described in several games' Pokedexes as being a signpost for spirits. Basically, where there is a Drifloon, there are spirits. Many paranormal investigators believe there is a strong connection between ghosts and electrical and magnetic fields. They are not only drawn to electrical fields, but they increase them. Increased magnetic or electrical energy is usually a sign of paranormal activity. Whether Drifloon itself is attracted to the electrical energy, or if it is attracted to the spirits that are drawn to that energy is uncertain, but it makes sense that Drifloon would be drawn to Valley Windworks.
But wait, there's more! When you're moving down Route 205, it's hard not to notice the giant windmills surrounding Valley Windworks. There's nine of them. I know. I counted. These windmills circle the building, and they are its main attraction. Why are there nine of them? That's random, right? Why not ten? Why not eight? I tell you, whoever constructed Valley Windworks was practically begging for a Drifloon's presence. Let's explore.
In a number of different cultures, nine is an incredibly unlucky number associated with death. In Japan, where Pokemon was made, by the way, nine is considered an unlucky number because the word for nine, ku, sounds too much like the word for suffering, agony, or torture; many hospitals in Japan lack a ninth floor or ninth room, simply skipping the number because of its perceived luck. In other cultures, nine is the number of heaven, and its number holds a significance with death and passing. Then, there's of course the creepy. Beethoven wrote exactly nine symphonies before he died. Lady Jane of England, often referred to as "the Nine Days Queen," was executed for high treason after ruling England for just nine days. President William H. Harrison, the United States' ninth President was the first to die in office. In Christianity, Jesus died on the ninth hour of hanging on the cross. As you can see, the number nine has all kinds of connections with death and bad luck. Why would there not be spirits at a place surrounded by nine windmills? Drifloon chose prime real estate in Sinnoh.
There is still the mystery of Fridays. Why did Drifloon frequent Valley Windworks on Fridays? Fridays, you guessed it, are a day perceived to have a deep connection with bad luck and death. In Jewish culture, Friday is the optimal day to die, as it is the day before their Sabboth, Saturday. Dying on Friday will ensure that you pass easily into heaven on the day of rest. In Christianity, Jesus was crucified on a Friday. Some scholars believe that Eve tempted Adam with the forbidden fruit on Friday. And we can't forget that Cain slained Abel on a Friday. Finally, there is the Western obsession with Friday the 13th, and how unlucky it is perceived to be.
I mean, of course there is a freakin ghostly balloon Pokemon signpost of spirits hanging out at Valley Windworks on Fridays. Why wouldn't there be?