you find it in the galactic HQ
You will need Galactic key and this how to get Galactic key you will need to talk to a Galactic team mate by the Galactic HQ.
With the Galactic key you can unlock any locked doors in the headquarters.
U can get the galstic key when you are in veiston city and go to the galactic ha and the guard to the right will drop his key
you have to go into the warehouse and beat everyone there to get the galatic key
you use it in the warehouse i think
All you have to do is Batlle him and get the Galactic key card
You find it in the Galactic Headquarters after they capture Azelf, Uxie, and Mesprit.
To get into the Team Galactic HQ in Pokemon Diamond you will need the storage key the Galactic Grunt leaves behind, and the Dusk Stone. If you can't get the key, it may mean you have not completed a mission.
you go to the other side of the base
there is this team galactic guy in front of the HQ in veilstone and he would give it to after you talk to an another galactic guy who tells you that he gave it to his partner
Galctic Headquarters is actually the Team Galactic Veilstone Building, but you'll need a Galactic Key to enter most of the doors.
You use it by going up to a door that it locked press A and it will open.