go back to twinleaf and restart the route to eterna city. Twinleaf-orbourough-florama-eterna. talk to everyone you see. you will get the hm cut. teach it to a pokemon. beat the eterna gym leader. cut the trees down.
when you need to save the three lake Pokemon from team galactic there is a guy that is standing in front of the big building in vielstone, talk to him then he will run off somewhere and he leaves behind a pokeball pick it up and that should be the key... sorry if im wrong.
you go to the bigger building on the right hand side of veilstone and find a way in from there
Vielstone Pize Exchange right next to Vielstone Game Corner for 20,000 coins.
You either use cut, to go to the Galatic building, or you defeat the gym leader. After that, you go to Hearthome city.
Drifloon is there every Fridays or when you beat team galatic talk to the dude in wind works building and Drifloon will probally show up.
In Vielstone city
Go to the Vielstone Galatic building in Vielstone Cityand talk to Cyrus. Once you beat him, he'll give you the ball. If I were you, I would use it on Crescilia, Uxie, Mesperit, or the other pokemon that runs away.
There is a small one in Eterna City and a big one in Vielstone City.
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
in the vilstone warehouse next to the galactic building
Veilstone City at the very top.
You get one from Cyrus at the Vielstone building. or action replay
go to the veilstone building where there is a door locked there is a galatic grunt there
in the galatic building in veilstone city!
You find him at the Vielstone Building, aftergoing to Lake Acuity, after getting seven badges.
release the lake Pokemon in the Galatic HQ building
near eterna city team galatic building