Oh, sorry, I guess it's not obvious, but you can hit Boss 13's head for a little bit less damage than hitting the body. It doesn't have a hurtbox either, so you can safely pogospam.
Viewing post in Waddle Knight (Kirby Fangame) comments
I BEAT THE TRUE TRUE FINAL BOSS YEEEEEEAAAAAASSSSS
https://youtu.be/lVNHD4RiXBM (captions coming soon)
tldr, got some absurdly lucky HNs which allowed me to survive longer
Really fun Kirby fangame, I thoroughly enjoyed it, though re-learning Hollow Knight's controls (I use the keyboard default) after being used to this game's controls is going to be tricky lol.
edit: now i have >30 videos of me dying to said boss, idk what to do with them lol
edit 2: Is there a sort of "Theater" feature in this game for viewing cutscenes? I kinda forgot about what the earlier cutscenes said :P
edit 3: ill just dump all the unlisted footage of me dying to stuff in a random playlist that ppl can seek out if they wish to ig