Marlon? [Thinking for a minute...oh, he's one of the other Gym Leaders we haven't met yet besides Drayden in Opelucid.] He's the Gym Leader in...Humilau City, right? I can't say I've had the pleasure of meeting him yet, but I wouldn't be surprised to hear if he was considered a tough Gym Leader to face as well. [But then again, Cilan likes to think the best of his fellow Gym Leaders as obviously tough competitors and being hard-workers... Unless you're Skyla maybe.]