Hey, another Game Maker project, neat! I think this is a solid base for a shmup, but it's really, REALLY lacking in the most important part: gamefeel. Shooting enemies has no feedback (to the point I wondered if I was even doing damage), and getting hit has no feedback, which is why I assume you have such a huge healthbar, but nothing _feels_ particularly good. In addition, every enemy has SOOO much health, which is just ridiculous and makes you feel weak. I kept getting powerups from Kylo and not noticing a difference-- A very important concept in shmups is zako enemies that die in one hit, so your ship actually feels like it has power! A lot of shmups have enemies that die in one hit! The bullet patterns themselves were quite well done, but there was a very noticeable lack of depth-- There were mechanics randomly introduced during the bosses (though I don't think they really... made the bosses any more interesting? In the first fight the wormholes were cool but never really "helped" me attack the boss since I could only shoot him from below and he kept covering up below him with a barrage of bullets), but during the actual stages it's basically just micrododging and shooting for minutes until an enemy finally pops. There's no sense of "progression."
I will give huge props for Kylo though, he's extremely charming. Very adorable little fella. Has a LOT of personality. I'd say you should play more shmups and think about the "little things" that make games like these _feel_ good, and then try to inject those elements + the same whimsy from Kylo into the game mechanics as a whole. You have potential, keep at it!