World 3 - Level 8
This level consists of one central region and four smaller towers - each representing a different puzzle. Move Stinky into the red teleporter to get to the central tower. Switch to Loof, and release the Kaboom! You don't need any boxes here, so you can either just evade Kaboom! or use the boxes to destroy him. Collect all coins and exit through the teleporter as well.
Move the Reflector in the lower-right corner one field up and one field left. Fireballs will destroy all boxes marked with a yellow "x". Now move one of the remaining boxes into the yellow teleporter. Make sure you push the box into the teleporter from below, not from the left. This will allow Stinky to teleport to the upper right tower, cross the stream using the box and step on the purple button. Loof can now collect the coins.
Move Stinky to the lower-right tower (blue teleporter). Push the Reflector along the yellow arrow, and immediately position yourself at the yellow "X" to avoid fireballs. Then push the second reflector along the green arrow to blast a way to the Rainbow Coins.
Now to the lower-left tower (green teleporter). Enter the teleporter from above (!) and follow the yellow path by immediately stepping to the left. Push the two boulders into the water along green arrow. Exit throught the teleporter, and re-enter from the right (!) so that you enter along the purple arrow. Push the boulder into the water to reach one of the coins. Now do the exact opposite (i.e. start by entering from below) and use the remaining three boulders to build a bridge to the other coin.
Finally, enter the central tower again. Use the remaining boxes to build a bridge to the exit. If you dare, build bridges to the Bonus Coins as well. Be prepared to evade Ghosts (escape through teleporters, if necessary).