How do you get inside the headquarters of team galatic in pokemon diamond

Question

How do you get inside the headquarters of team galatic in pokemon diamond

Answer 1

if its in veilstone u need a key a guy drops i think message me where u r

Answer 2

After team galactic steals all lake pokemon you sould find a hencmen in frout of the headquarters and he drop the key also try youtube.com

Answer 3

You have to get a key card from a guy near the arcade. Talk to him a few times to get it. But he might not be there till later so just see if he there. Hope it helps.