Single element champion dragons can be a tricky bunch and there's no one dragon that can win on everybody's game so the suggestion i give you may not work. However, I'm going to suggest using a dragon that was previously released on a Dragon Tale anyway. The following may work: Merfolk, Sunken Prince, Seawitch, Adrift Princess, Seeker, Cursed Rose, Dame of Darkness, Ghost Armor, Lord of Light, Arbiter, Neo Fire, Playful, Banshee, Dark Omen.