having read nietzsche for an assessment of moral agency to write an in depth philosophical paper i would have to say that nietzsche is not the best choice for a debate argument. First, I am not saying that Nietzsche is a nihilist; he is exactly the opposite. The more imporant distinction is the kriticism would turn itself. The action of the K influences the morality of the judge in the context of the round. This application of influence turns itself because you are asking the judge to identify your moral advocacy as his or hers. This means you are requiring a slave morality from the judge. Nietzsche followed the same lines as Kierkegaard in saying that you must determine your own moral code and live by it. The application of the K fails to remain consistent with the ideas Nietzsche suggests.
In response to the Scu i would not say that Nietzsche is inherently existential, but the nature of the master slave morality follows closely one of the major themes of the existential movement. Personally I fail to see the value of any existential argument in terms of the debate community, merely because of its focus on individualism.
There might be some good debate ground in Nietzsche's perspectivist arguments, I am not familiar enough with them to qualify that statement.