Board Thread:Naruto Discussions/@comment-38071683-20200117152211/@comment-9782468-20200117155658

I'd say Minato's base Rasengan is as strong or stronger. Minato developedit to its furthest point without Shape Transformation so all base Rasengan should do approximately the same damage. And Minato's base Rasengan was about the size of Big Ball Rasengan.

But as soon as Konohamaru introduced Wind Release to his Rasengan, it became stronger than any Rasengan Minato was capable of in life.

That's my interpretation anyways