Indeed, Fooruman is difficult. The way I go about defeating him is this:

Stand on the ground and get hit by spikes. That takes off one heart. Let the tube turtles fall. That takes off one heart. Immediately after they hit you, jump up and grab a cheshire cat on the side they fell on. As soon as you start falling, get yourself over to the other side of Fooruman. Rinse and repeat.

It works for me.