This is a good game and I like going directly to all the bosses and fighting them instead of having to walk or wait in any way. The game rules change quickly enough to keep the gameplay interesting - I was surprised at the second boss until I realized that I was affected by gravity, and then I understood the idea of the game. I also loved that the game announces when the boss attacks, so that you are prepared. This would usually be done with animations, but since it's a jam, this works too.
For things to improve, I think that for one thing, the boss should not teleport so far away every few seconds, since our movement speed is not that fast and it takes a lot of time to run around and chase it. Another thing is that I didn't know the boss died because the door that appears is very small, and the boss kept moving, so I thought the game was broken. Luckily I ran into the door. Lastly, I think our attack range should have been indicated with a box also, just so we knew how close to get before attacking. I didn't understand why I wasn't attacking or why the boss wasn't dying until I knew I had to get closer.
Still, this boss rush is very fun, and it's rare to see a game made with pygame, so that is also very cool.