Kun wins Force. Scourge and Bastila are utter non-factors and would be one-shotted easily. Malak goes down everytime without putting up too much of a fight, either.
Not sure about sabers only. Malak is good enough to challenge him, but Scourge and especially Bastila will be plowed through almost instantly.
All-out goes to Kun, especially if he makes liberal use of his powers (which, well, he probably won't).