alright now lets discuss the other element dragons.....
like the Earth Dragon, we will need help to decide what he is capable of doing
the Thunder Dragon, we will need either Sasuke, or Kakashi to help us out with him
the Wind Dragon, we will need Neji, myself, Naruto, and a few others to help us out with him
the Fire Dragon, all Uchiha's will need to help with this due to the fact that we are the Fire Masters. I honestly think that the Fire Dragon's weapon should be a Flamethrower that burns hotter than any fire jutsu, but that is not as strong as Amaterasu due to the fact that ability is only able to be used when the Uchiha has Mangekyou and Eternal Mangekyou. Able to heat the surrounding area with just its pressence.
Now about your Water Dragon, I honestly think that his Breathe weapon should be something like a HIGH powered force of water......able to rip the area apart. His other ability should be when he is in a water area that he should be able to turn into water itself.
The Wood Dragon, we will need Yamato's and Shodaime's help with this dragon for his abilities and powers.
The Ice Dragon, we all ready have his breathe attack and his normal ability. But shouldn't his very pressence Freeze the surrounding area?
I know all these dragons seem overpowered......but the thing is they are Dragons the masters of their element. They are quite literally the element themselves.