Capt. Stern is in the Museum where all the the Aqua/Magma members are conjugated around.
In the port at Slateport City.
He's on Slateport City's museum, second floor.
You have to beat the Dewford Gym then go in the museum in Slateport where there was a long line of Team Aqua, he's on the second floor.
its at the top part of slateport;go to the northernmost part of the city then take a right. hope this helped
Slateport City doesn't have a gym.
Its in Lilycove or Slateport. Its in Lilycove or Slateport.
It's in the top right hand corner of slateport city.
Vermillion City is in Knato and Slateport is in Hoenn; you can't.
he is in the laboratory in slateport that has many boats and near the bazaar
he's not in there! he's in slasport city his worker is in the abandoned ship and he asks you to find the generator or something i forgot then you have to find it and then you go talk to him and he will tell you to go to captain stern and then go to slaport city and then he will trade you for something. hope i helped :)
he is in the museum upstairs you should heal your Pokemon because you have to face two magma grunts once you talk to him.
there is no gym in slateport, the next gym would be in mauville with electric pokemon