he is at the lab
Go to the library in Canalave city after you fight your rival their and talk to prof. rowan, after the story go lake verity then to lake Acuity near Snowpoint City
Go to Lake Verity. When you enter, Prof. Rowan will be there next to a Galactic Grunt. He'll say to go help Dawn/ the dude (I don't know his name. Sorry.) Anyway, you'll have to get passed 4 Grunts then commander Mars should be there. Defeat her and go to Acuity Lake and she will be there.
you have to go to lake verity first then go to acuity.
Go to Lake Acuity with a Pokemon with Surf. Surf to the Middle of the Lake and go into the Cave. Uxie is in there (Lake Acuity is up North by Snowpoint City)
Did you go to the other lakes cause you need to go to lake acuity at the end and you need the HM rock climb.
ya don't! it looks like you do but what you do is turn around and go back and go in mt cornet and go to the ACUITY LAKEFRONT! (where rowan sent your friend) now figure out the rest on your own
After you have 7 gym badges and go surf from Jubilife city to Canalave city. Then go to Canalave cities library. Go all the way up the library floors then you will see professor Rowan. Then he'll talk to you then a rumble starts, go down all the floors and come out of the library and again professor Rowan talk. to you again and fly to twinleaf town (lake Verity) or fly to Pastoria city (lake Valor) or Snowpoint city (lake Acuity) and there are lots of Galactic grunts. Ands that's all!! I hope I helped!
Mars does not appear at lake acuity. If you beat mars at lake verity then go to the upper part of mt coronet and explore until you reach snowpoint city. If you're at lake acuity and beat Jupiter then go to the galactic HQ in veilstone city.
After you go to lake acuity you must go to mt. coronet and catch giratina. After that,the major blackout in sunyshore city finishes off and you go there and battle the gym leader.
Go to the place it is on the map
Go to lake valor...
Go to the pysduck with the SecretPotion.