Randomizer is the 27th Advanced stage of Challenge Mode and World 4-7 of Story Mode in Super Monkey Ball 2 (66th Advanced stage and World 4-11 in Super Monkey Ball Deluxe); it is also the 126th stage of Ultimate Mode without continues (106th with continues).
This stage has three long platforms, the lowest of which has five columns of squares spanning its width and the blue goal. The middle has three columns of squares and the green goal, and the highest has one column of squares and the red goal. Each of the squares has rounded peaks and valleys that alternate in a checkerboard fashion. There are two single bananas on the lowest platform, two banana bunches on the middle platform, and four banana bunches on the highest platform. The monkey will bounce randomly (hence the stage's name) depending on how you are angled on the squares as well as how fast you are going.
Simply hold up and adjust your speed as you get close to the goal.
Zigzag on the start platform, and position your monkey on either the leftmost or rightmost column of squares. Stay straight; and as soon as you gain enough height, position your monkey onto the middle platform, and slow down to avoid falling out. You can also push forward on the control stick from the start, and you will be bounced up to the higher platform. Slow down gradually without changing direction, and you should make it to the goal.
Do the same strategy as for the green goal; but when you land on the middle platform, try to keep your monkey centered on the first or third column of squares. When you gain enough height, carefully land on the highest platform. Adjust your speed, and roll into the goal. You can also push forward on the control stick, moving at maximum speed from the start, and you will be bounced up to the top platform where this goal lies. You will have to be more careful with reducing your speed for this goal. Because if you do it wrong, you can easily get bounced off the stage or to a lower platform.