If he is unregistered he is a Pinto, and could be registered as a pinto, he can NOT be registered a paint w/out both parents being registered APHA (American Paint Horse Association).
Paints are not crossed w/ many other breeds (atleast and not registered APHA), they can only be Paint, QH, and Thoroughbred.
Pinto is registered on color (they don't accept horses w/ app charactoristics, or if I'm not mistaken drafts).
So w/out knowing your horses parents are registered APHA, then I'd say he's a pinto! If you want to have him registered, you can, as a pinto!
And a Paint can be double registered as a pinto!