Nice little game but the bosses having randomization sucks. Mostly SS I don't feel like I'm ever improving when I fight him I feel like I'm getting lucky. Also, him instantly blasting your ass when you take down his elemental shields while the hazards are still on screen is bullshit. The player should get a moment to get ready before the next shield pops in. I know complaints about difficulty are hard to make without looking like a bitch but you have to admit that's a fair point.
Also while on the topic of the elemental shields I don't think he should throw a twinkle chaser at you during them until you hit him once. It would be best to give the player a bit to get what the hazard is before giving it an extra thing to dodge.