Well, ain't this a bother for him. Not only does he have to work with others, but he'll likely have to either trust four other people with information on his ability or continue to deceive everyone. If it's the former, he's not going to stand much of a chance when he's pit up against any of them. He could just tell everyone he turns his arm into a cannon, and the guy he fought will confirm this to everyone, but then he'll lack the flexibility his ability gives. And once he starts using another power, people will know something is up with his ability, especially the guy he fought before.