You need all weapons,life-ups,subtanks(full),and full health.get to the 3rd cart in Armored Armadillo's stage and ride it to the boss door.jump before u hit the wall and grab on to the uper wall and climd up.a capsule should be there.NOTE if the capsule isnt there make sure u dont get hit(at all!)to use it press UP RIGHT DOWN and have full health AND it will kill every boss(excluding Sigma)!