you can't! :(
you have to evolve ur eevee in d/p and then trade it back on ss
You do not use a stone, you need to go to the Eterna Forest ( Flowroma town is faster) then go to the mossy rock& battle until eevee evolves into leafion.
you have to have an evee and level it up by the stone in the first forest you go through in the game.
no you can trade soulsilver pokemon to black
he is not in Pokemon soulsilver or Pokemon heartgold
POKEMON SOULSILVER come with a poke walker and the Soulsilver game
Pokemon soulsilver and Pokemon heartgold are basically the same game just different versions but i do recommend buying Pokemon soulsilver
SOulsilver
if you levels up eevee near it, it evolves into leafion
You CANNOT LEGALLY download Pokemon Soulsilver.
You can't catch bastiodon in Pokemon soulsilver.
You'll need to trade for it from Pokemon HeartGold. It is not avilable in the wild in Pokemon SoulSilver.
there is a mew in Pokemon soulsilver but you need to catch all leadndery Pokemon including event Pokemon