This hack is quite interesting and very technically impressive! very cool that you actually got the Underchomp RPG mechanics working for other fights.
I think it's a bit disappointing that you can barely try out all of the cool combat options without almost guaranteeing a defeat because the boss is so strong, meaning that the only real viable strategy is doing Flip with Mario a few times and then Thudley + Bowser until he's dead or you are out of FP. It's still fun to try through your combat options though and it's fun in general!