I don't think Pokemon from in game trades can be shiny, after reading a bit about it.
From the information I can gather, the Pokemon you are traded is preset and is not coded to have a chance of being Shiny, and therefore you cannot recieve a Shiny from the trade.
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No, Not from In Game Trading :( Serebii Says You Can only Get Shinies through wild Pokemon, eggs, and the battle tower.
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You can find shiny Pokémon in the wild, in eggs, and in the battle tower, which is basically everyplace you can catch a Pokémon save for the Battle Tower in which you won't be able to catch the shinys there.
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So, after reading all of this, I've concluded that it's not possible to get a shiny from an in game trade, so the Spiritomb you trade for is therefore not shiny.
Hope this helps! :)