To defeat N.Gin, shoot at the flashing pads on his robot suit. Four of the pads on the first suit will fall off. The pad underneath his viewing area will not fall off: it will just stop flashing. The two easiest pads to hit are the ones that fire missiles, (the middle is also quite easy too), then his arms are the last two. When he brings up his arm, there will be a few seconds before he starts firing, so this is the best time to shoot at the end of his arms. When you have destroyed all the flashing pads, then he will get into another suit which is even harder. This time, the flashing pads are four missile launchers, one on the far left, and one on the far right. The last one is just under N.Gin's ugly mug. Hit and destroy all these pads, and you have and apple bazooka!