Yanma and most other Pokemon have new evolutions that only exist in the 4th generation Pokemon games diamond, pearl, platinum this means none of these evolutions exist in the previous generations like leafgreen.
You can't evolve Yanma in Leafgreen. This is because Leafgreen was made before Yanmega was made. So basically in Leafgreen, Yanma is a Pokemon that can't evolve.
You'll need to trade for it from Pokemon LeafGreen or Pokemon FireRed.
No only in diamond, pearl, platinum, heartgold, soulsilver, black and white will yanma evolve.
Yanma can't be found in Pokemon FireRed or Pokemon LeafGreen; it is strictly a fourth generation Pokemon.
You can't catch one in Emerald. You'll have to trade one from FireRed/LeafGreen.
Yanma is a Bug and Flying type pokemon.
yanma does not evovle. yanma will only evolve in Pokemon diamond and pearl and platinum.
yanma needs to know ancient power to evolve into yanmega. it will learn ancient power at lv 32 and lv it up again and it should evolve ino yanmega.
it eloves at a high freindship lavel
Yanma can sometimes be found on Pokemon Diamond, Pearl, and Platinum in the Great Marsh in Pastoria City. You could also catch and evolve a yanma from HeartGold or SoulSilver (found on Route 35 during a swarm) and trade it over to your Pokemon Diamond version. Yanma evolves once it learns AncientPower. You can obtain yanma on Firered or Leafgreen version in Ruin valley and migrate it over to your Pokemon Diamond, Pearl, or Platinum version have it learn AncientPower...and there you have it, you're very own yanmega.
Yes, Yanma is actually extremely rare in Pokemon Pearl and Pokemon Diamond.
You cannot get a Yanma in Pokemon Emerald, as only Hoenn Region Pokemon can be found in Pokemon Emerald.