Power Bomb Guardian
The Guardian is exactly like the plants that shoot at you when you transform into Morph Ball and try to solve a puzzle, except MUCH BIGGER. When you start, you will see a point near the floor where you can spider ball up the wall. Wait for the dark Sporb to shoot a bomb and then Spider up the track as fast as you can. You can either use boost (not reccomended) or bombs and timed falls to go to one of four bomb slots. When all are triggered, the Guardian is killed. GO TO THE HARDEST SLOT FIRST! As the battle progresses it launches bombs faster, and if you fall off you will start all over again. Needless to say, not good for speed. MAKE SURE YOU ARE WELL TIMED! Wait until you see where the power bombs are going. Also, don't forget to take your time. If you don't, you will end up taking even more time trying to beat him/her/it.
Kirzath's Tip: The power bomb guardian fires its bombs so that if you keep moving in the same direction as when the guardian launched its bomb, it will hit you head on. Use this to your advantage. Right before it fires a bomb, move in the opposite dirrection. Once the bomb is in the air, keep moving to where you were going. The bomb will miss you by a mile, and you can avoid every single attack this way.
For speed (and the faster this is over the better anyway), use stickyboost.