There are multiple ways to reach the score required to complete a challenge. Like building a very long combo chain to increase the score very quickly before clearing the level or aiming carefully for every single block to get the maximum clear bonus. The following guide uses mostly the first method.
Most of the time it consists in building a combo chain up to 30 or 40 hits before aiming for objectives.
The first level is rather easy compared to the next ones. You can build a combo chain on one side, then continue with the other side. Can can also reset your combo chain between the two sides. This level is large enough and with only a few obstacle to train your ball control with back-hits and do only two combo chains during the level. Once you reach 950 points, you can end the level.
This levels has some closed areas. Start with the hardest ones like the one on top right and bottom right while the ball is slower, then continue with the area on the left. If you can manage the speed, you can clear the area around the warp gate. Once you reach 1100 points, you can end the level.
Aiming is very difficult in this level because of the numerous attract blocks. The center area allows to start with a long combo chain by positioning yourself in the right angle on the blue blocks. Once 10 hit combo is reached, aim for the keys while trying to maintain your combo chain.
The warp gate is well bordered and can be aimed at even at high speed. This leaves you enough room to unlock a high clear bonus, even with short combo chains. Once 1300 points are reached, clear the level.
This level is very obstructed and have only few safe areas. The area on top left is hard to reach and contains a fairly good number of blocks, which makes it a good candidate for starting. Clear this area before aiming for the one on the right, going through the column at the center and clearing the blocks around the warp gate (which won't be clearable once it is opened). Finish with the bottom left area which is more bordered.
Long combo chains are hard to build because of the amount of obstacles which makes the trajectory of the ball hard to predict. After your first two combo chains are broken, use the arrow aiming to build short chains with precision to reach 1350 points by unlocking the clear bonuses before clearing the level.
The long range aiming challenge. This level has very few empty area to control the ball and has no area dedicated to building a combo chain. You'll have to play with the attraction and bring the blockers in less annoying areas by guiding them while the ball is traveling through the level.
There are only a few exit area, you can build a 10 hit combo in the center area and collect the keys, while leaving one to avoid ending the level before you get enough points. If your combo chain is broken, you can restart a new one from the corners. End the level once you get 2250 points.
This challenge is rather easy once you can anticipate enough to avoid the lateral exit channels. With a lot of opportunities to build long combo chains, it is rather easy to build a huge one. Start by building a 10 hit combo chain from the central area from the bottom, then get the top keys. The one on the right is harder to reach. Then continue with a combo chain of 40 or more, or slow the ball to end the level with 3040 points.
Reaction challenge. This level quickly becomes messy. Start from the area around the portal which is hard to reach and send the ball in the center area. This area is rather safe, you can build a very long combo chain from there by focusing on the top or bottom area as long as the pink balls are outside. Then aim for the remaining keys, especially the one on the left if there wasn't any opportunity to take it before, then finish the level with at least 3030 points.
If your first combo chain was not long enough, you'll have to aim for more blocks to unlock some clear bonuses before entering the warp.
This level can take on your nerves. The goal is to constantly turn around the level to avoid the sparkler while building a very long combo chain. If you can, try to stick the ball in the lateral entrances. When the ball becomes too fast, slow it down and restart. End the level with 3120 points.
The chaotic structure of this level make the ball rather safe to bounce a bit everywhere. Start from the bottom right area near the red block which is the hardest one and send the ball back in the middle when it gets too close to the edges. And let the combo chain go longer.
When not that much blocks are remaining, start aiming. The ball can be pretty fast in the end, but that shouldn't be an issue if you cleared the previous challenges.
Like level 2-final, level 3-2 will test your reactions. With a huge amount of obstacles the ball will quickly reach high speed and will be hard to control. Start building a combo with the 6 blocks on the top left then get the nearby key. You can push the pink ball away before it gets in the way. Then focus on collecting keys while maintaining your combo chain until the ball becomes too fast. From then break your combo to revert to a manageable speed and finish by aiming precisely. You'll need 4030 points before clearing the level.
This level may feel like level 3-1, with large empty areas with little exits but a lot of interfering things. The area on the left is good to build a long combo chain, the one on the right is far more difficult to access and allows to end the level. Start from the left and collect some keys, then when you see an opportunity, grab a key from the right side.
To create an opportunity, the ball must stay in the upper or lower area to lead the sparkler, but the paddle must stay in the opposite area to attract red balls.
The final challenge is not that hard by itself once all the other challenges are cleared. The level is still terribly difficult. You'll require a lot of control and accuracy to quickly get the keys from the outside area while things are still manageable, then keep the ball in the inner area to collect the remaining keys. Each missed bounce makes you lose some time and let the mobs get out from the center area. The combo chain will grow without great efforts, the number of keys and the clear bonus can compensate relatively short chains. Lowering the visual effects can help to see better what is happening. 5000 points are enough to enter the warp and clear the challenge. Good luck.