Actually, I think that Aquarion is a better choice for Celestia, Luna, and Twilight.
Solar Aquarion - The sun (Princess Celestia)
Aquarion Mars - The stars (Twilight Sparkle)
Aquarion Luna - The moon (Princess Luna)
Plus, Solar Aquarion's Mugen Punch involves it punching its opponent TO THE MOON.
If that doesn't sound like a move that would be fitting for Celestia, I don't know what would be.