You can't. You can transfer Pokemon from your GBA games to Heart Gold, however.
Trade it of a gba game or of a cheat
Transfer from GBA via pal park OR Trade with HeartGold/SoulSilver.
Yes, you can trade them if you attach a wireless adapter to your GBA. You can also migrate pokémon from a GBA game to HeartGold/SoulSilver by putting them both into a DS.
You have to trade it from a GBA game that has it.
No, but you can trade Pokemon only in HeartGold to Black
Kyogre is only available for Pokemon: Sapphire on the GBA. Ho-Oh is the legendary pokemon available to you in HeartGold.
You can migrate GBA Pokemon to a DS Pokemon game but you can't trade using the GBA game trying to trade with another GBA game.
Through the GBA slot.
you can trade pokemon from heartgold to black but you can only transfer the pokemon in heartgold not trade it from black
Lugia cannot be caught in Pokemon Diamond/Pearl/Platinum. You can trade for one from HeartGold/SoulSilver or migrate one from a GBA Pokemon game via the Pal Park.
If you want to trade Pokemon from a GBA game you can migrate 6 Pokemon a day at the Pal Park in the Kanto region. If you want to trade Pokemon from the newer games (HeartGold, SoulSilver, Platinum, Diamond, Pearl, etc..) you can go to the bottom floor in any Pokemon center
yes. you can trade Pokemon from diamond, pearl, or platinum to heartgold or soulsilver.