Lovely work! All the little touches that went into animations everywhere, how much variance you managed to create with all the same attacks. I can't imagine how much of a pain it was to code the duplicate boss near the end there! All the personality that went into each movement, and nothing complex, no deep story or hidden meaning, just a boss fight. I think this is truly what flash games are meant for, just these fun little titles. No need for grand adventure, just have something fun and show it off. Kinda inspires me to start creating something controlled like this.
It's a 5 from me dawg. Good work.