Can you discriminate a monooxygenase from other enzymatic mechanisms by the requirement of NADPH? I am working on a project about CYPs 450. It seems that most of them function as monooxygenases but there are other categories as well.

Assuming that the question makes sense, is it correct to say that CYP 450 monooxygenases always require the presence of a regenerating system (NADPH) as opposed to other CYPs 450 which are NOT functioning as monooxygenases?
I would say this is not a correct statement.  The main reason being that just because an enzyme is not a monooxygenase doesn't mean it doesn't require a regenerating system for NADPH.
Examples would be many dehydrogenase, hydroxylase and synthase enzymes. They also require NADPH regenerating systems to operate efficiently.  So, one of the CYP 450 enzymes may fall into any of these categories requiring NADPH/NADP yet not be a monooxygenase.