What if your in the old chateau with the national DEX but when you go up to the TV it says something is glaring at you but nothing happens

You need to go to the old chateau at night not at day or in the morning. If you go there and it still says "It appears to be staring at you" check back in 1 hour. When it has a question saying if you want to look into the TV, answer yes. You will encounter a rotom.
Make sure you have a low level Pokemon to weaken it first as it is only level 15. It has levitate so don't use a ground move. it is electric/ghost. That's all folks!