How much difference does changing the strategy within each round really have. I tend to just let the boxer box with his natural abilities and it tends to work as good or better than trying to use different boxing strategies within the game.
Maybe you could also have the trainer provide a recommended strategy for each round and you can make the decision to go with that strategy or choose a different one, better trainers with great ringside skills should give you an advantage with the recommended strategies, you could have an option in your game setup to display recommended trainer strategies for each round or you could turn it off. Those strategies would obviously depend on the opponent and the boxers strengths and weaknesses and be influenced by the trainers actual skills. Just a thought.