[Without wind] the ninja doesn't seem to go as far as you aimed for him. When that makes the difference between a perfect score or not, it can be pretty frustrating.
So I challenged the grand master, then backed out after I saw his stats. A few weeks later I was challenged by some other trainer and he used the same monster, Driaga (or whatever it was, that's close anyway). After defeating this subpar monster-- it had less than 1/3 the stat's of that which belonged to the grand master--- the game declared me the winner of the platinum cup and began the victory sequences.
it did finally end the battle once I selected the heal skill. for a moment it showed the enemy health as 87/87 (which was never the hp of the komodoom), and then returned to the negatives with the correct max hp before finally letting the komodoom die and terminating the battle.
Fighting a komodoom. poison took it's hp to the negatives. the battle did not end, but continues without my being able to select any actions. Health regenerates and energy bar charges.
the 5% health steal attribute goes away after a few turns in battle. I presume its a passive skill that should remain the entire battle.
 "Sticky Ninja Academy"){kind=icon}
 "Monster Arena"){kind=icon}