Streets of Rage 3: Yamato

Streets of Rage 3, with Axel on Hard
The US version of this game is far harder than the Japenese version, Bare Knuckle 3. Some even say that BK3 on hardest is even easier than SOR3 on easy.
This boss is pretty easy to beat, if your able to keep him off the screen. It's when he breaks out of his routine that he becomes a nuisance