I believe (i havent played sinoh in a while) that you go to the marsh city chase the galactic grunt and you get the key by going in the lake hopez i could help
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A key to the Galatic world. In the Galatic world there are alot of dumb Galatic people and they are all named MAX STABS
the key you got from the team galatic grunt dropped is not the one that's for the team galatic ware house you need to open the ware house door with that key and fight your way through it to find another key and that one is for the team galatic main building. You can get additional info here at the related link. (good luck!)
The Storage Key opens the Galactic Warehouse in Veilstone City. It is dropped by a Galactic Grunt in Veilstone City after you beat Jupiter at lake Acuity.
First there should be a galactic grunt outside the headquarters. Talk to him to get the key to the warehouse. Go to the warehouse which is also in veilstone city. In the warehouse you should find the key to the headquarters.
you have to beat the snowpoint city gymleader go to the lake by it then go to the front of the galatic velstone bilding talk to the grunt in front of it and he will drop it