Unfortunately, the few descriptions I could find concerning the conduct of the Cuban Revolution, are highly suspect. Like most propaganda, the narratives are mostly apocryphal.
Fidel, I suspect, wasn't much use for training the new recruits. He hadn't demonstrated any capacity for battlefield leadership during his aborted raid on the army barracks at Moncada, the one that landed him in jail. Also, during the stay in Mexico while his men were training, Fidel was constantly engaged in raising funds for his invasion. Ultimately, the only references I could find that mentioned Castro's participation in battles referred to the fact that he fired the first shot signaling the commencement of an attack.
Raúl Castro and Camile Cienfuegos were Fidel's chief lieutenants during those early days. Camile, hardly known in America outside of Cuban-American communities, probably was Fidel's best field commander. His photographs reveal a man of intelligence and humor, the kind that soldiers like to follow. It is doubtful that Raúl would have held any position of importance except by nepotism.
Che was the doctor although he groused continually that he wanted to fight. However, he had no training and, ultimately, proved to be an inept commander, especially at the Bay of Pigs invasion. That left about eight Fidelistas to provide training to approximately 200 recruits. I calculated that they must have been divided into platoons of about thirty each with one Fidelista assigned to lead them in the capacity of a sergeant I supposed. These would be manageable training units.
Every recruit brought their own weapon as Castro had none with which to arm them. One can only imagine the problems this created with supplying different caliber ammunition. How they were able to train these men to move, shoot, and communicate, as a combat team is the stuff of legend. I really enjoyed speculating as I wrote Rebels on the Mountain.