Okay, we are deffinately being trolled.
I have been searching for clues or ages about Minato's chakra. But there is crap all. In the 4th movie, all they hint us is that when the LR is being preformed that his chakra is green, but Naruto's chakra has changed preforming rasengan before to. So that didn't helpus at all.
But this is where I was thinking that Naruto will become knowledged on the LR. Because even though in the 4th movie their memories were erased, I highly doubt Minato thought of that on the spot... Which then lead me to think there is someone else he practiced with ( possibly Jiraiya)
Now here is the problem. Even though it may be documented somewhere... how in the hell do we figure out Minato's chakra... because right now there are only 3 people who can perform a rasengan; Naruto, Kakashi, and Konohamaru.
Now does anyone have a theory on chakra for Minato?
*I was thinking it was wind but we have no full proof. But then I thought what if you need someone with the same chakra element to preform this? Which continues my thought on how it is wind. Not to mention chakra nature can be hereditarily meaning it is a 50/50 chance (or some shit like that, don't troll that comment for I know they don't always have their parents nature.) that Minato was a wind chakra user.