There's a question to be considered though: If Hoopa is malevolent, and Giratina is the equivalent to Satan, doesn't that mean that there has to be some sort of relation between the two?
Personally, I'm of the belief that if Game Freak really wanted to give us Poke-Satan, they would go out of their way to include it in the story, and with a major part of it as well.
While Giratina certainly has six rings (which I'm realizing could be another link to Hoopa actually, but likely not), six wings, and six legs, I believe that if Pokemon Satan was to really be incorporated, it would involve Arceus too. Yet although Arceus certainly banished Giratina in Poke Lore, he never goes down to seal up what would be the source of all evil.
Hoopa is similar to red in color. This by itself isn't proof, but keep something in mind... It was stated that every Pokemon, one way or another, would be made available in Gen VI.
I have yet to see Arceus.
As a result, it's likely that Arceus is being saved for a larger plot... And with the massive hoop-legendary plot in ORAS, it becomes even more likely that said plots will intertwine.
As a result, I see that it must be clear. Hoopa could only be Pokemon's Satan, regardless of Giratina. If they're setting up a Post-Dex legendary this much, then there aren't manny other options.
This is, however, purely theoretical, but it would make sense.