Ken Rosewall was a serve & volleyer but in comparison with the other Australian stars of his era he varied much more the other net approaches than them. He could play the 1-2 punch approach right after his serve, the baseline approach or the chip & charge and his results were excellent. However, because of this lack of serve & volley (in comparison with his rivals), he made on average 20% less points with the volley than them.
Offensive - Very High
Ken Rosewall didn't play enough baseline rallies (as did most of his rivals) to really represent the Punchers. Besides, his backhand was mainly played with slice which is much more the trademark of the Offensive players or the Retrievers. The only time he Punched a bit his forehand is when he used the forehand approach.
Puncher - Medium-low
Ken Rosewall wasn't a Server at all because only 12% of his first serve in were unreturned and this result was below all the other Australian stars of his era. He dominated with this shot and had to find more solutions on his return games to counterbalance it.
Server - Low
Playing more baseline rallies than his rivals, Ken Rosewall won 45% of his points by the errors of his rivals (which was 10-15% more than them.) Although he was more an Offensive player, he could also Retrieve.
Retriever - Medium
At the time of Ken Rosewall and the other Australian stars, the Tempo players didn't really exist. It was all about serving & volleying and from the back of the court they had much more a Punching technique than a Tempo one. The take backs were rather big and the two-handed backhand (trademark of the Tempo players) weren't often used.