Nenufar Dragon

Breeding
You can get this dragon by breeding a Water Dragon with a Plant Dragon at the Breeding Mountain or Ultra Breeding Tree.

Breeding a Water Dragon with a Plant Dragon may also result in a Coral Dragon.

Nenufar Dragon somewhat resembles the Pokemon Bulbasaur and it's evolutions, Ivysaur and Venusaur.

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