You can't catch one in Emerald. You'll have to trade one from FireRed/LeafGreen.
You cannot get a Yanma in Pokemon Emerald, as only Hoenn Region Pokemon can be found in Pokemon Emerald.
You'll need to trade for it from Pokemon LeafGreen or Pokemon FireRed.
Yanma evolves into Yanmega which is a Gen 4 Pokemon. Ruby, Sapphire, and Emerald are all Gen 3. In other words, Yanma doesn’t have an evolution yet.
You can find Yanma in Pokémon Diamond in the Great Marsh.
route 121
Pokemon 118 is Yanma, you get it in Union Road. But to get Yanma, you need a Pokemon to knock it out of a tree.
Yanma is a Bug and Flying type pokemon.
yanma does not evovle. yanma will only evolve in Pokemon diamond and pearl and platinum.
Trade with FR/LG.
Yes, Yanma is actually extremely rare in Pokemon Pearl and Pokemon Diamond.
On Union Road. It is spelled Yanma, by the way.
Yanma can't be found in Pokemon FireRed or Pokemon LeafGreen; it is strictly a fourth generation Pokemon.