I know spiritomb has this weird stone in his sprite and I had gotten it (called old keystone) and I put it in the tower but after I put it in all it said was that the tower's name is the Hallowed Tower. What did I do wrong?
You have to talk with 32 People Undergound. This can be achieved by having 2 physical copies of DPPT and a hardware to play the Games on.
Source : Experience