I'd accept if you guys said something like:
Shodai Was Wood manipulation: Water, Earth
Nidaime was Water manipulation
Sandaime was Fire, earth manipulation
Yondaime could be Wind Lightning.
as in every hokage had different element types..
But not with: its a ball! He is wind!!
And I'd be more inclined to say that he is Lightning chakra...
Kakashi also said it was very common for a jounin have atleast two chakras manipulations..
A hokage level user should atleast control all 5 nature chakras.
Making it very hard to say he is that or that..
So we can say that he could create a rasengan with any element avaliable, or even better a dual element rasengan..
More flashbacks with skills are needed to draw a good conclusion