...how would you feel about a legendary duo based on the Christian God and Christian Devil, with a legendary based on Cthulhu being their counterpart? --- "The greatest pleasure in life is doing what people say you can't do." ~Walter Bagehot
Yeah, that's as close as you're ever gonna get to God and Satan in the Pokemon Universe. Hell, Giratina even has six legs, six wing things, six spikes and was banished (presumably by Arceus) to another dimension for its violence.
That aside, I'm totally down with the idea--Pokemon would likely keep it fairly subtle, almost a generic light and darkness conflict (I didn't realize the Gen V dragons were based on Tao until seeing it on Gamefaqs).