By observing his actions. When he is able to host the events that he was trained to host' date=' smoothly and knows how to handle any situation that might occur. Well, I would train them myself, then I would pick the best ER(s) as trainer(s) (when I see that he/they knows what everything's about. I'm not sure, but the staffer should be mature enough to not be biased, not start any foolish arguments, take responsibility for his actions, know what actions to take, respect people. Basically just understand and follow the mod protocol.