I found the first phase of the battle to be somewhat difficult, but with patience and concentration, I got through it easily. Then the started started, and I thought "Oh, crap!!" The lightning threw me off guard, but I figured out I could play tennis with him (redundancy, much?) and utilize the lightning as well. In a sense, fight fire with fire. It took me multiple tries, but I beat him after a couple of annoying failed finishing blows.
I finished Hero Mode recently and I found that I was able to beat him on the second attempt (using that upgraded super potion, to mention).