She is in the Sinjoh Ruins. This can only be accessed with bringing an event Arceus to the Ruins of Alph.
Chat with our AI personalities
noyou cant battle Cynthia in soul silver. Even though she appears in the Arceus event, You cant battle her.
no you can trade soulsilver pokemon to black
you meet Cynthia by going to the sinjo ruins (show an arceus to the president at the ruins of alph) and she will help you get a sinnoh legendary egg (Palkia, Dialga, or Giratina) amd then the unown will warp you back to the ruins.
You CANNOT LEGALLY download Pokemon Soulsilver.
You'll need to trade for it from Pokemon HeartGold. It is not avilable in the wild in Pokemon SoulSilver.