Viridian Forest
go into veridian forest in kanto (after the elite 4) and the 2nd to last patch of grass has pikachus. They are very hard to find, so be patient. Hope i helped!
As many as you can get
They are in veridian forest 2. Usually one random wave of pikachus go during that level.
Yes, Pichu is in SoulSilver. It originated in the Johto region. It can be found by breeding two Pikachus.
Trophy Garden. You can also get Pichu there.
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
Yes, Santa can make Pikachus, and all the other kinds of Pokemon. Also, he sometimes gets donations from the Pokemon factory because they like to make kids happy too.
SOulsilver
To acquire Group A Pokemon in the Yellow Forest route (which in this case, are the Pikachus that can Surf or Fly) you have to walk 9500+ steps to be able to encounter pikachus that can surf and you have to walk 10,000+ steps to be able to encounter pikachus that can fly.