At least 2 badges are needed to trade from leafgreen to firered.
yes with wireless adapters or a link cable
In firered, it is in the powerplant, but you can't get them in leafgreen. You have to trade it from firered.
you have to obtain the ruby in firered/leafgreen and trade it via link cable. this is really the only way other than cheats. sorry. unless you have firered or leafgreen, its not possible
Bellsprout has to be found wild, in leafgreen, you need to trade from Leafgreen for Pokemon.
You can only get Rayquaza in Pokemon Ruby, Sapphire, and Emerald. If you want to get a Rayquaza in Pokemon Leafgreen or Firered, you will have to get a second Game Boy Advance or SP with a link cable to trade Rayquaza into your firered or leafgreen.
No one in the game trades you rattata nor pidgey if you want to trade those Pokemon use a link cable or wireless adapter to trade with leafgreen or another firered.
You must trade pinsir from leafgreen to firered.
Slowpoke is not in firered only leafgreen can get it trade one to firered to get it.
Vulpix is an exclusive pokemon to Leafgreen version if you trade one from Leafgreen to Firered you will be able to have it.
Poliwhirl is not obtainable in leafgreen trade one from firered.
slowpoke it unobtainable in firered, trade one from leafgreen
trade eevee from leafgreen or firered.