Winning 54% of his points by the errors of his rivals Guillermo Coria was a dominant Retriever. His main game plan from the back of the court was to wear the rivals' backhand down and to execute it (against right-hander) he used the backhand cross, the forehand down the line & inside out. Besides forcing his opponents to miss more shots than average he possessed all the weapons a real Retriever needed: an effective pass, lob, touch & jaw dropping drop shots. He was by any mean one of the greatest clay court Retriever of all time.
Retriever / Very high
From time to time Guillermo Coria could take risks with the Punching forehand but this shot was much more used to Retrieve than to attack. This explained why he made on average 30% less points with the forehand than his rivals.
Puncher / Medium
Guillermo Coria couldn't count on his serve to win a match at all. He was often (not to say always) dominated with that shot by his rivals and had to win his match from the back of the court.
Serve / Very low
To complete his Retrieving game style Guillermo Coria could also come in to get an edge (Offensive). In total 13% of his points were won at the net (with or without a volley to play) and this result stand in the average of the ATP players. His favorite way to come in was the baseline approach with the forehand. He could also use some drop shots to move forward.
Offensive / Medium
As a great defender Guillermo Coria could counterpunch or take his backhand on the rise when needed like a Tempo player. However, he was much more a defensive than an aggressive baseliner and couldn't be regarded as a Tempo player.