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.
No, Not from In Game Trading :( Serebii Says You Can only Get Shinies through wild Pokemon, eggs, and the battle tower.
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.
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! :)