In battle tower you now succesfully go to the in final stage, but when you enter, you see just a grave and three strange pokeballs nearby a grave... untill from the grave start moving and now from the ground you see a white dead man and looks like not even a human anymore...

Now a strange man turn his head to you and with creepy and creaking voice said.

"You’re… here... I’m trapped... And I’m lonely… So very lonely… Won’t you join me?"

Now a dead man grab one of his three pokeball.

Spoilers: Be carefull, maybe you can controll his Gengar and Muk, but defeat his pokemon "White Hands" it's very difficult, but if you want to be alive, then you should try to defeat them all!