I've thought about this one myself as an intellectual exercise, though I went totally different directions with it. For starters, the only Superior putting on a direct appearance is Lucifer, in his incarnation as the End of the World. That and I chose to make Utena human.
The Duelists are a group of Celestials (And a Soldier; see below) who are fighting for the power of the Rose Bride, an enigmatic Ethereal who promises the power to grant 'World Revolution'. I haven't decided how -precisely- to work it, but she essentially has a portion of the Godhead that managed to stay coherent in the aftermath of the Metatron's death. Well, allow me to rephrase that.
It's the Word of Light in Remnant form. You see why Lucifer's involved. He wants it badly, but somehow the Rosebride is stymeing his efforts at simply taking it from her. But he thinks that if someone else were to get their hands on it, he could take it from them. And so he has inspired someone to join into the Duels: A human, Tenjou Utena. After all, taking it from a Celestial, who understood what it was they had and could use it fully, would be dangerous. But a human?
It just struck me that making Utena a Celestial would be somehow missing the point of the series. Now the rest of the cast is most certainly not human:
(Not entirely sure)
Touga: Balseraph of Malphas (Trying to out-manipulate Lucifer, no less. Silly Liar.)
Nanami: Impudite of Malphas, with a cadre of human hangers-on. (Poor Tsuwabuki)
Saionji: Calabite of Baal. I originally was thinking Djinn, but this place is rather thick with them. Somehow Calabite works for him well. He's a Beast. What he wants, he takes. What he hates, he destroys.
Juri: ...the hard one, if only because she's my favorite of all the duelists. If Infernal, I see her as a Djinn, though I can't for the life of me imagine who her Prince is. If Angelic, I imagine her as an Outcast, though again I'm having a hard time figuring what she'd be. Suggestions?
Shiori: Impudite of Kronos. (diediediediediedieDIEdiediedieDIE)
Miki: Weak-willed Cherub, Superior uncertain (though Jean or Eli would both make sense), attuned to his 'sister'
Kozue: Djinn. Such a Djinn. Scary Djinn. Comments about her serving Andrealphus are no doubt just spite on my part.
Phillip, the Happy Shiny Mercurian
"The World needs more Shoujo."