What would you like for your Darkrai? I have a shiny Nidoking if you're still looking for that. I also have shiny UT Moltres, shiny UT Mewtwo, and shiny UT Deoxys I can if you're interested in one of those.
A shiny nidoking isn't worth a darkrai, that pokemon is crazy hard to find legit. You give me shiny nidoking and shiny moltres and you have a deal. Because i had to trade to of my shinies to get this darn pokemon.