I don't know if i'm late or not, but I randomly was checking on the site and seen this topic and arguments.
The argument for Minato beating muu (easy) is Minato uses clones (lets assume 4), Muu goes airborn and invisible. The clones then split up, Muu Splits (invisible). Muu using the same speed onoki used on Deidara (which is fast on it's on) sweeps in and out from the sky slicing each clone.
