Then randomize normal enemies.
No thanks?? I am unsure what you are trying for here
they also provide a "difference in kind"
That's precisely why I dislike them
I spend hours upon hours perfecting my movement so I can get through stages without ever pulling any brake, learn how to avoid every enemy in my path, quickly dispatch a few that would slow me down otherwise, and just in general enjoy jumping from one platform to the next..
And then randomly I'm stuck in a tiny room where I suddenly have to fight some giant monster and everything I learned up to this point is useless; platforming is gone, movement is gone, avoidance is gone, etc etc etc - I'm magically forced to play an entirely different game?
Bosses are cool when they are extensions of what I previously learned, in a more forcing manner (eg I get a Hookshot type item, play around some with the Hookshot to learn how it functions, and then I go into a giant area with a boss whom I have to fight by quickly and smartly maneuvering through the area with said Hookshot), but way too often the boss levels are (intentionally) designed in a way that they have nothing to do with the rest of the game -
I play Sonic because I want to play a momentum based platformer that, when executed properly, allows me to go at insane speeds; not to be in a tiny 5x5 pixel box and stand around afk waiting for Eggman to come back on screen so I can jump on his head and then afk again.
Imagine you played Portal, and every 3 levels you'd lose the portal gun and be stuck in a car where you first have to beat your adversary by outracing them, and then only get to advance after beating them in a fistfight.
Maybe this fistfight has engaging combat, and maybe the racing controls are quite fun.. but ultimately this is not what I play Portal for, and Portal isn't hurt one bit by "being repetitive" because all you do is walk and solve puzzles with your portal gun.
Nobody would get the idea to do this either, because it is, plain and simple, rather .. silly! But in platformers for some reason it is established and "necessary"?.?
Again, if you can make a boss who keeps the general gist of the game alive (and in Indivisible that will most likely happen by virtue of the combat system alone - since you are going to fight Bosses just the same as any other enemy, and the enemy-fighting is clearcut from the platforming sections) I'm all for them, but the usual "Ok, the last 20 hours you practiced how to pin-point-land on a 1 square tile out of a running jump, now let's shake it up a bit and just require you to do something that has nothing to do with the entire rest of the game" (see also: Battle Levels in Dustforce) I can't stand