a fish museam
Talk to the remaining aqua member in the museum in slateport city.
Go to the ship yard south of the museum
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
To get past Team Aqua and access the museum in Pokémon games like Pokémon Ruby, Sapphire, or Emerald, you typically need to defeat their members blocking the entrance. First, ensure you have progressed enough in the storyline to have access to the museum. After dealing with Team Aqua, you can enter the museum, where you may need to interact with various characters or complete specific tasks to advance the plot.
A team aqua grunt gives it to you in the slateport museum after you defeat them all.
Capt. Stern is in the Museum where all the the Aqua/Magma members are conjugated around.
Captain Stern will be in the Oceanic Museum. There will be Team Aqua members outside. They will once clear when you go into the shipyard when you will find a man beside a table. Once you talk to him, the Aqua members will be gone and you can enter the Museum for $50. Hope this helps!
go to the shipyard and talk to some dudes
you want to beat them in 2ft. of that ,,libary,, its museum.
you have to go to the big place with the boats and talk to a man at a table their. after that, the museum is clear, and you can go in. after that, talk to one certain of t team aqua members and he will give you a TM. then just march upstairs.
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.
Did you see the museum with all the Aqua Grunts blocking the entrance? South of that is a large brown building with a sign next to it. Go in and Cap. Stern is the one at the table looking at the blueprints for a ship. Talk to him, then you can enter the museum. Before you move on and fight the grunts, talk to the Aqua Grunt right north of the exit of the museum. He will give you TM46 Thief. Hope I helped.