Level 99 has 4 tubes, 11 penguins. Just power up a couple tubes and wait until all 11 has gone through. Restart.
Level 88 has a tube and a belt that lets you send 2 penguins back and forth for the entire time of the level.
Here is a picture for your reference:https://imgur.com/a/FM1Vxhr
Power up the tubes and belt shown in red. As soon as the second penguin enters the middle tube, switch the direction of the belt shown in gold. This will make the two penguins go between the left and middle tube making for very fast sending through tubes.