Where is the outside stand in Pokemon Colosseum?

There isn't a specific location called "the outside stand" in Pokémon Colosseum.

However, it's possible you're referring to the "Stand" in the "Underground" area. This is where you can:

* Train your Pokémon

* Battle other players (using the "Shadow Pokémon" to fight)

* Buy and sell items

The Underground is accessed via a manhole in the middle of Phenac City.

Let me know if you were looking for something else!