Defeat Monty (the Python).
Defeat Robert & Sir Galahad.
Defeat Eyesore.
Defeat Monty (the Python) while doing damage at least once before swapping back to the Ninja each time and without failing
Defeat Robert & Sir Galahad while doing damage at least once before swapping back to the Ninja each time and without failing
Defeat Eyesore while doing damage at least once before swapping back to the Ninja each time and without failing