Can you have a meowth in Pokemon Emerald?

yes,you can.

you can trade a skitty for meowth in battle frontier. I'm sorry but at the moment i can't remember the building where the guy who trades you is.(you can't have meowth in ruby and Sapphire because there is no battle frontier)

Yes you can.

First go to the Battle Frontier then walk to the Battle Tower, but don't go inside.

Enter the house directly left of the Tower and talk to the girl. You'll have to trade a Skitty for the Meowth.

To find a Skitty, search the area right of Rustboro City (I believe Route 116?).

It's the area between Rustboro and the cave entrance. Hope this helps :)