I do know what the Rotodex does. I would say that it is one thing to use it when battling CPU charecters such as the totems or Team Skull, but to use it against another human player is different, espically if the other human player does not have the Rotodex as well. Personally, I am unsure of how fair it is to use in leauge matches. But either way, since they have never seen such a thing before, they can't have a rule against it. But, one would possibly be added after the battle.