A quick script I threw together to determine the last two bytes of a shiny pokemon's PID. It will also edit a pkm file or generate the possible pkms for you if you want.
http://pastebin.com/20prdT3u
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Devil's Survivor Savegame Editor
Feel free to use it however you'd like. I really only made it as a proof of concept to show that pokecheck only adds trivial obfuscation by hiding the last few bits of a PID for non-public pokemon. If you can do something useful with it, awesome.