There are three secrets of the old chateau that are pretty cool yet creepy at the same time.

1) The main event, Rotom. At the night zone of the game, go to the old tv in that one room. Then thud it and you will find Rotom.

2) There are two also rare pokemon in the old chateau. The creepy Haunter and Gengar. At the night zone of the game, Go to the creepiest room, the one with the picture with the red eyes. Just walk around and you'll eventually find one of the creep couple.

3) The curse of the old chateau. When you go into the room with the red-eyed picture between the intermission of the hallway and the room, let go of up and press it again. Then, when you are inside the room, for the 1st few seconds, you will see the ghost of a girl in the room on your right. That is the creepiest, and the best part, is thatyou can do this one any time of the day.
I hope you've enjoyed this segment of cheats. And if you know what's good for you, you will try them. Happy Cheating.