The idea that you need to focus on breaking parts is solid. But to make meaningful decisions I'd need to know what the enemy is capable of with each of their moves/body parts. It could be as simple as a line of text showing <x> used <body part> to <description of the move> whenever they do something.
Since there's a heavy focus on breaking parts maybe it could get rid of the general HP bar, and only have HP for each part, but have one of the parts be "critical", and you win by destroying that part specifically (like where the central operating system is for the mech and vital organs for the kaiju).