As an SFPA speedrunner in practice, I’ve developed my own strategy for the final boss, but it’s still a bit slower than your strategy where you lock him in place somehow at the beginning of the battle. How is that done, exactly?
Well, in the latest versions of the game, the glitch has since been patched. I'd love to see your strategy for the boss fight, though.
Well I haven't taken any footage but I can try to explain it.
Basically start the battle by luring ink pants into the corner of the map. From there perform the following steps: ink dash INTO him so that you both overlap in the corner, then immediately turn around and charge a swing for half a second, then release so that ink pants into locked into the corner again and fp is gains a bit of distance from him. Use this distance to repeat the process until you beat him. Occasionally ink pants can escape the lock by simply dashing away from the corner, but it's pretty rare since he was programmed to respond to attacks by jumping or attacking. I'll take some footage when I can and send it to you so you can get a visual example.