Given eight points on a circle that are to be labelled with three binary digits, we can easily find a labeling where all adjacent points have Hamming distance one.
I have also found examples where the average Hamming distance is equal to two, for instance [000, 011, 110, 001, 100, 010, 111, 101]. But is it possible to find a labeling where each adjacent pair has Hamming distance two?
edit: Forgot to point out that we're looking at the distance of ADJACENT pairs.
With distance 2, you can never get from the points having zero or two 1-bits to the points having one or three of them, so the answer is no.