Popeye spanked the Sea Hag at least once in one of the late cartoons, those limited-animation things they did in the 60's. (Of course, in the comic strip, he was an avid spanker, of Olive Oyl and others.)
Also, I was surfing late night TV some months ago and came on a Johnny Quest cartoon where someone was spanking a princess in front of Johnny. I have no idea of the context.
There is also a very early Betty Boop cartoon -- back when Betty was still a dog -- which ends with her and her friend (Bingo?) giving each other initiation spankings.