In 2008 I had the easy badge and was missing one from the second medium badge. Thanks to badge of the day I played this(unnecessarily) for a while and finally got those last 2 badges!
When you are fighting the second to last boss(the one that splits) leave one little piece alive and dodge his few shots while your health recovers.
On the last boss: Crash into the rocks on purpose. They barely hurt, and the boss will then dive into them AND he won't hit you with his very painful dive attack