How do you get altaria on Pokemon SoulSilver?

At sky pillar you can find altaria but its rare.

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You can get a Swablu and evolve it...? I think it's somewhere around Fallarbor Town...yes..it's somewhere around Fallarbor Town. There's a bridge there down from the old man who gives you TM Roar, go down that bridge and search in the tall grass, beside the cliff that has A LOT of indents in the wall where you can make a secret base.