There is one big issue with the first boss. It slows down when there are at least 3 or 4 balls on screen. And since there doesn't seem to be a limit on how many balls can be on screen aside from the normal SMW OAM limit, it can potentially slow down to a point where it is unplayable.
As for that Dark Pyramid level, this is an issue I keep seeing a lot in SMW hacks. Stop applying HDMA gradients to the foreground and sprites. I don't care if it looks cool, because it affects gameplay. It makes sprites in certain positions hard to see for the player, and it can make much more blind jump situations than normal. Especially with the weird way SMW handles vertical scrolling. If you want to convey some sort of dark effect, apply it only to the backgrounds. At least don't make it harder for the player, especially since this level doesn't seem designed with the gradient in mind from the start.
This hack is pretty nice, graphics are well done, levels are mostly easy, there are lots of powerups. Level design is pretty linear so I would recommend to mix it up a bit.
However there's this issue which you didn't fix, I even pointed it out in my comment under the previous demo:
Originally posted by Atari2.0
this flicker that occurs when the save prompt appears on the overworld
That needs to fixed. If the next demo you submit still has the issue, I'm not gonna accept it until it gets fixed. I let it go past twice already.