World 9 - Level 6
House of Mirrors
Before you make each move, carefully study the pattern of the fireballs to find the right timing and potential safe spots.
Switch immediately to Loof. In the first room, push the reflector one step along the yellow arrow and get to the yellow safespot "X". Then push along the right green arrow, and move (one by one) to the two green safe spots. Push up along the blue arrow and get to the blue "X" safe spot. Finally, pushing the reflector down along the white arrow will make it easier for Stinky to follow your path later.
In the second room, use the yellow arrow/safe spot, then the green, then the blue, then the white. Loof is now safe. Switch to Stinky, and move Stinky up as well (you should be able to get through with a little timing - again, study the fireballs carefully before each move!).