In order to beat the last boss, you need to hit him in the nose about five times. After you hit him, he'll jump into the air. Run to either corner and wait for him to descend. When he's about to land again, run to the other corner. (If he is in the corner, his hands can't hurt you.) Now wait until he starts moving and breathes fire. Pay attention to which way he is going because you need to jump to the back platform as soon as he starts moving again after breathing fire. You will hit him every time using this trick. He will speed up after 3 hits, but just be patient and you will get him.