Hi Nancy,
This is how I did it:
SPOILER ALERT
Place Stinky as shown in the yellow circle.
The easiest way to do this is to wait for both cannons to fire and then make your move.
Switch to Loof.
The boxes with the yellow Xs:
Move them to the yellow Xs.
Run away from the Kaboom!
Move the boxes to the white Xs.
Run to the yellow "dot".
Once the Kaboom! enters the room, trap it when it's at the white "dot".
Collect the exposed coins and bonus coins.
The boxes with the green Xs:
Move them to the green Xs.
Run away from the Kaboom!
Place the box with the dark blue X at the dark blue X.
Move the boxes with the green Xs to the light blue Xs. When you do this the Kaboom! should be above you.
Trap the Kaboom! when it's is at Loof's starting position.
Pick up coins and bonus coins.
The box with the purple X:
Move it to the purple X.
Wait at the purple "dot" for the Kaboom! to walk across the box.
Hurry to place Loof somewhere at the top of the room to the right.
Switch to Stinky.
The box with the grey X:
The box with the grey X is needed to trap the Kaboom! in the grey circle. So it needs to be moved to Loof's starting position. It's very important that the Kaboom! is not allowed to cross the box in the water again (It will be blown up by the cannons. If you can't manage to move the box with the grey X in one go, you can take a breather with the box on top of the box in the water.
Once you trapped the Kaboom in the grey circle, remember to blow it up in the middle.
END SPOILER
Good luck

Mette