It is for catching Spiritomb.
You can't. The Odd Keystone is only obtainable in Diamond, Pearl and Platinum. You will need to trade a Pokemon with an Odd Keystone to get it on SoulSilver.
you get an odd keystone underground
The Odd Keystone is given to you by a man on route 208
Talk to 32 people underground and mine for an Odd Keystone. South of Soleacon Town put the Odd Keystone in the Altar. Then, catch your Spiritomb!
A spiritomb will apear unless you hav'ent met 32people in the underground.
He's at the Hallow Tower, but you requires to have the Odd Keystone and talking to 32 people total in Sinnoh Underground
You must have an odd keystone. You then go to the Hallowed Tower, and use explorer kit. Then it will say, "put in keystone?" or something like that. Say yes, and spiritomb will jump out.
go down to the man in fighting clothes he doesen't whant to battle talk to him
You can find Spiritomb in Pokémon Pearl by completing the side quest. Before players begin the quest they need to find the Odd keystone.
where you put the odd keystone in
You take the odd keystone to the hallowed tower and then you get a spiritomb But you have to do other things to. I think you might have to beat the pokemon league
you press the a button on it when you get the odd keystone. to get spiritomb there,you have to meet 32 people underground.