There is no doubt that a few things in the Pokemon world are pretty weird or creepy such as Lavender Town and particular Pokedex entries. What is the creepiest/scariest thing you have seen/heard/read in Pokemon? This can range from music, to Pokemon, to particular episodes of the anime, to places, to NPCs dialogue and characters, etc.
For me, the creepiest thing in Pokemon is the Unown Tune from GSC on the Radio. It's even creepier than Lavender Town to me. After reading/watching playthroughs of Lost Silver, I can't listen to that song anymore.