Yes you can migrate pokemons in Pokemon soul silver. you can either migrate from emerald, ruby, sapphire. im not sure about leaf green and fire red.
Migrate it from Pokemon (Hoenn version)
It is impossible to move a Pokemon from SoulSilver to Sapphire as the two games are from different generations, you can only migrate Pokemon from Sapphire to SoulSilver.
Trade from HeartGold or migrate it.
no you can't but you can migrate in into diamond and then trade it.
Trade it from Pokemon HeartGold or SoulSilver or migrate from Emerald.
Through the GBA slot.
You can't. But you can migrate Pokemon from Pokemon Emerald to the Pal Park in Pokemon Diamond, Pearl, Platinum, HeartGold, or SoulSilver and transfer them into Pokemon Black.
you can migrate him from emerald or sapphire.
No, you cannot migrate Pokémon from Pokémon Yellow over to SoulSilver.
you need to migrate it from Pokemon diamond/pearl/platinum. it is unobtainable in soul silver/heart gold trade, not migrate
First, you need to migrate your Pokemon in Sapphire to Pokemon Diamond, Pearl, Platinum, HeartGold, or SoulSilver. Then, you need to migrate those Pokemon to Pokemon Black.
migrate from saphire, emerald, or ruby version