Imagine if you were like a koala and ate only one kind of food. what kind the fool would it be?

Eucalyptus leaves. Koalas usually eat eucalyptus leaves or other leaves of trees native to Australia.

If I lived near an area with eucalyptus, that is what I would like to give him. Other than that, I know koalas are kind of healthy and they eat plants (and if given to) veggies. So I would probably try to keep them on a sort of human diet type of thing.