there are only 8 rare Pokemon in soul silver (articuno,zapdose,lugia,entay,hoho,rioku,moltress,suikune)
Pokemon silver is more rare than gold but Pokemon crystal is more rare than Pokemon silver or any other Pokemon game.
You get it in Mt.Silver (Rare)
mt silver
train, or rare candy
yes they are preety rare in crystal they are really rare in gold and silver
everywhere but very rare
action replay
Route 2 but it is very rare.
Route 45(Rare)
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Well, you can catch some rare Pokemon there like Larvitar.At its end you will also get to battle Ash of Kanto.
you can find rare candies anywere in kanto and johto. You just have to be lucky