Coral Dragon

Plant Dragon + Water Dragon
Water Dragon + Plant Dragon = Coral Dragon or Nenufar Dragon

Damage Calculator
To explain, when attacking with Water, Coral deals double damage against Fire and Electric, medium damage against Water and Ice, and no damage against Plant. When attacking with Plant, Coral deals double damage against Electric and Dark, half damage against Water and Plant, and no damage against Fire. When defending, Coral takes double damage from Earth and Ice, half damage from Plant and Dark and take no damage from Water.

Counter Dragons

 * Dinosaur Dragon
 * Earth Dragon