Sorry for not being helpful. I can't remember the last time I went online in this game, and I don't think I've ever done co-op, to be honest.
I still stand by my original statement, though. Co-op is not going to help you with this. It would just end up being a crutch. You have to keep doing the boss fight over and over again until you become familiar enough with the patterns to die less often. For some people, this is two hours. For others, this is two weeks. Take notes if you have to, and make sure you understand why you die when you die.
If you want to see how speedrunners handle all of the different patterns that Kalameet has, you can watch any of the videos on the All Bosses leaderboard.
Gonna call you out here for being weird
Also, I'm weird as well
How do you want to settle this?