depending on how long it takes you, samus has less armor in the final scene...she's in a bikini for me =)
matty the boss you are talking about is called "serris"? the easiest way I've found is to stand on the 3rd platform in and kneel, then just wait till she comes straight across at you, missle her in the head, grab onto the ceiling, after she flies past you, kneel back down on the platform, the only time you have to worry is when she flies horizontal at you and is flashing