To defeat the final K. Rool (in the sub) easier, pause the game when he starts firing the lower sparks from his generator. Normally it will diffuse on the metal barrel, but you can dodge it completely by pausing the game when the lower spark appears. If done correctly, the end pieces will remain on screen, but the middle will be still moving. Wait until it completely crosses the screen before resuming the game. Proper timing is important, as mistiming will result in a long spark that fills the screen.