I managed to get collision detection on the boss and onion rings in the boss part of the stage. But while playing the main part, I feel like the clouds aren't fluffy enough and I don't know what to do about it because I tried to make them as fluffy as I possibly could.

I also managed to get rid of the onion rings and boss when he's defeated. After trying to write 0s to clear the map and failing, I tried making all the colors in the background palette the same, and sure enough, that did it. I also got rid of the onion rings. This involved putting their positions off screen but I was still able to run into them. I found the reason why: I had not written their changed x positions into VRAM. So I did and I wasn't able to hit an onion ring when it was off the screen anymore.

So now with the main game part in and the boss part in, I can now begin working on putting new levels in. But I'm not going to do that today because I got sick of programming. I had to go to sleep with a half-broken program. It was about 4 a.m. when I decided I had to give up for the time being and go to sleep. But I fixed everything today. I don't know how, though.