Beat Jupiter or mars after getting azelf
You will have to find the secret key for the galactic Head quatres in veilstone city? Try that then if it doesn't work search on google for a different somewhere and don't ask me where the key is I got my brother's m8tes to do that bit for me. It cud B somewhere in the ware house to the left or sumthing!
They're there to keep you from going to the gray part of the game