While Lavender Town is an already dark subject matter for the Pokemon series, these fan theories only manage to increase the creepiness surrounding this mysterious town.
Lavender Town Syndrome
This theory states that on February 27, 1996, many Japanese children by the ages of seven and twelve committed suicide after the releases of the Pokemon games, Pokemon Red and Pokemon Green. According to the rumor, there were high-pitched frequencies within the games that only children ranging from 7-12 could hear. These frequencies would then lead the children to suffer through headaches, insomnia, and many other ailments. In the worse case scenarios, the child affected by the game would ultimately commit suicide for unexplained reasons. It is believed that the suicide rate was so severe in Japan during that time, that it ultimately led to the Japanese government covering up the mass suicides from the public.
However, what ultimately disproves this theory is the fact that no such high-pitched frequencies exist in the real world, and that if this tragedy were, in fact, true, there would've been major media coverage over the incident. Therefore, this theory is considered to be only an urban legend that started out as a horror story on the Internet. So this proves this "occurring" is debunked
Although, there are frequencies that only people who are in their teen or younger can hear. These have been used to prevent teens from loitering in stores, while not bothering their elders.
The Dead Raticate Theory
In the Pokemon Red and Green games, the player engages in a battle with his rival, Blue/Gary. Blue would send out his Raticate to fight with your Pokemon, and if you were to win against him, his Raticate would proceed to faint in pain. When you encounter Blue again, you notice that he doesn't have his Raticate with him, and you also notice that he's at the tower in Lavender Town. This tower is meant to be a burial ground for deceased Pokemon, and if you were to connect two and two together, you would realize that Blue's Raticate was dead because of you. You also manage to destroy Blue's innocence and dreams because of your callous killing of his Pokemon, and you even manage to take away his grandfather's love for him in the scene in which he chastised his grandson for losing to you, all while praising you for your accomplishment. Oh, and he's also an orphan. Do you still want to be the very best?
It is commonly believed that the video games concerning Lavender Town are possessed. An example of a supposed paranormal occurrence happening within Lavender Town would have to be with the supposed Pokemon Trainer, Buried Alive. As the story goes, Buried Alive was a boss in the original Pokemon Red and Green games, and that he was replaced by the Marrowak ghost in the later incarnations of the game. Buried Alive was an undead trainer who proceeded to challenge the player to a Pokemon battle. If you were to win against Buried Alive, the screen freezes up. If he were to win, however, he would proceed to drag the player's character sprite into the ground to devour him or her. His main Pokemon is believed to be a White Hand.
There was also a rumor that was circulating on the Internet about a supposedly haunted version of Pokemon Red and Green called Pokemon Creepy Black Version. In it, a multitude of the mysterious Pokemon known only as the Unown, eerily spell out the words "LEAVE NOW."