After you fight off team aqua out of the museum you will see a team aqua member, talk to him and he will give you the TM thief :D -also known as TM 46 :D
Captain Stern is on the top floor of the museum in Slateport City.
You deliver Devon's Goods to Captain Stern who is in Slateport City's museum.
Slateport City doesn't have a gym.
Vermillion City is in Knato and Slateport is in Hoenn; you can't.
Board the Ship which says Slateport city in Hoen
Oceanic Museum in Slateport City
You can find TM Thief in the Oceanic Museum in Slateport City. There should be a Team Aqua member standing inside the museum. Talk to him and he will give you TM Thief.
Talk to the remaining aqua member in the museum in slateport city.
On the quest on delivering the Devon Machine to Capt. Stern in Slateport City, enter the Oceanic Museum, in the first floor near the entrance, a Team Aqua Member is in there, talk to him and he'll give you the TM Thief.
In Slateport City, you'll have to go to a museum in order to finish an errand. Talk to one of the Team Magma members there, and he'll give you the TM Thief.
Theif can be obtained after beating team aqua in the ocean museum in slateport city, just talk to the team aqua member that's still inside and he will give you thief.
by Daniel Le: go to Slateport city the go to stern's ship yard ask the man at the front table. after that go to oceanic museum then go upstairs ask the man behind the computer then you battle team magma. and you can go to mauvile city
Dock is located at the Shipyard in Slateport City. You must talk to him in order for the Team Aqua/Magma grunts to move, allowing you access into the Oceanic Museum.
He's on Slateport City's museum, second floor.
In Eterna City, go north to the Galactic building then Cut the trees down. Then, don't enter the building, but instead move one step forward, then head east. In that little path use Cut once more to find TM46 Thief.
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 :)
Captain Stern is on the top floor of the museum in Slateport City.