Where can I get a salamance or the Pokemon it evolves from.?

Bagon (Salamance's prevolution) can be found in Meteor falls inside of the small room that you find the Dragon Claw TM. It will then evlove into Shelgon, then Salamance after you level it up.

It evolves from Bagon, which you can catch deep inside Meteor Falls. It evolves to Shelgon at lvl 30, then to Salamence at lvl 50. It's a bit of a grind training wise, but worth it. Good luck.

Alright, well, since you cannot get a Salamence in Pokemon Emerald without trading it to your file from another game, then I figured that you would like to get the next best thing. In this case, the next best thing would be Salamence first Pokemon form, the little dragon Pokemon, Bagon. You can find a Bagon in a specific area of the Meteor Falls cave, which is located west of Fallharbour Town. Bagon can be captured and found in the northeast area of Meteor Falls if I remember correctly. I might not be right on the dot, so you might have to do some searching but, you can still find Bagon in Meteor Falls. After you capture a Bagon, raise it to level 30, and it will evolve into the Pokemon, Shellgon. After that, raise the creature to level Fity-Five and you will have your Salamence. Hope this helps.

You can find a Bagon, a Pokemon that eventually evolves into Salamence, in Meteor Falls, in the part behind the waterfall. Obviously, you need surf and waterfall to get to the certain room where Bagon lives.

P.S.- It is rare and you can also find a TM02 Dragon Claw in the room.
Hope this helps!