Unlimited points
Find any area where there are two weapons. Pick up one weapon, pick up the other weapon, then repeat the process until you have enough points. You will receive them at the end of the stage.
Bosses
First Boss: Grenades
Machine Boss 1: Roll Kicks
Boss in portable tank on level 3: Roll Kicks
Level 4 Boss: Bead Butts or Roll Kicks.
Machine Boss 2: Roll kicks
King Pin: Head Butts