Most everything Ozzy records is just plain ol' double tracked...i.e., sung twice on two separate tracks. DLR did this on most of the VH recordings too.
If you have a vocal harmonizer and are limited on tracks (or looking to do it live), take a very very short delay - maybe 100ms or shorter - and pitch shift it down (or up) ever so slightly (use the 'fine tune' if there is one). If you're running stereo, pan the wet signal a bit to one side while sending the dry signal symetrically to the other side.
Chorus on a vocal will sound a little synthetic.