He's in the museum.
Go to Mt. Pyre if you haven't already done so. If you have, go to Slateport City and talk to Capt. Stern, and then return to Lilycove City to continue the storyline.
In Slateport city harbour you will see capt. stern being interviewed with a large crowd talk to capt. stern and you will go into the harbour thing and then go to their hideout in lilycove city.
You get it in Slateport City, by Capt. Stern. Hope I helped :)
While in Lilycove City, you can find Captain Stern in that museum place where Team Magma/Aqua are standing by. I forgot how to get rid of them, but once you do, you can find Captain Stern in that museum place I mentioned.
at Emerald: Lilycove city, u can win a masterball at Emerald: Lilycove city, u can win a masterball at Emerald: Lilycove city, u can win a masterball
From lilycove city if you go east you can reach mossdeep city.
in lilycove city
Go to Lilycove, battle your rival in front of the Lilycove City Department Store, and then go to Slateport City and talk to Capt. Stern. ^^^This information is incorrect and only taken from incomplete guides^^^ In Emerald: At My Pyre, you get a magma emblem. You need to go to the Mt Chimney Chair lift and take it up. Once up there, you start coming down the Jagged Pass. A little ways down the emblem will react and open up a cave for you. This is your next objective.
At the beginning of the game, he's in the house south of the Petalburg Forest, and west of Petalburg City. At the end, he'll be with Capt. Stern.
Lilycove City squirrel
It's in Lilycove City.
Nothing