Greek training is about adapting to and calculating an enemy's move and could quite often vary, depending on the threat faced. Unlike Roman training, which emphasises on "strength in numbers", Greek Training encourages practitioners to be assertive. It is about seeing what your opponent's next move is, then dealing with it, as shown when Percy said that he could tell what Ares' next move would be by the way his muscle tensed. However, conventional Greek tactics, notably the phalanx, was also used (as in the Battle of the Labyrinth).
After bathing in the River Styx, when Percy fought Hades' army of Skeleton Warriors, his Greek training mixed with his enhanced combat skills put his mind into "autopilot," allowing him to take down the whole group of warriors and pin Hades to the floor in seconds.
During the war games, Percy rolls under the defenders feet, slashes instead of stabbing like a Roman would, and whacking defenders with the flat of his blade, generally causing mass panic. When Percy is on the Hubbard Glacier, he uses his Greek fighting style to hold off a small army of continually resurrecting Roman ghosts, showing how effective this style is.