In SoulSilver Version, Rayquaza can only be encountered in the Embedded Tower after you trade Kyogre to the game and show both Pokemon to Professor Oak in Pallet Town, he will give you the Green Orb.
After catching both Kyogre and Groundon, you come with them in your team and it'll be there. Beware, you have to trade with HG to get Groundon.
Go to You Tube and search for Munching Orange how to catch Riquaza!
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
the last legendary in story mode is ryquaza and in free mode it is Latias
SOulsilver
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