Wow, this is one boss I liked (and grew to not like :p); he's fun to watch, but fighting against him? I pity the poor soul who has to endure it, because it was one method of attack after another, and with significant variations too XD
I liked how the music has a catchy theme, the pixel art was done very nicely, the boss's animations were very charming, and the inclusion of both player clones and boss clones made the last 2 stages very intense :o
Good job here, mate! :D