Perhaps you are thinking of a different location or item?
Could you please clarify what you mean by "unlock"? Are you looking for:
* A specific item or Pokémon: If so, tell me what it is.
* A way to access a particular area within the stand: If so, please provide details about the area you're trying to reach.
* A different location entirely: If so, please tell me the name of the location you are trying to find.
Once you provide more details, I can help you figure out how to get what you're looking for in *Pokémon XD: Gale of Darkness*.