>>56873289professional: a person engaged in a specified activity, especially a sport or branch of the performing arts, as a main paid occupation rather than as a pastime
if he's making a living off of videos about nuzlockes, then by definition he would be a professional. one could argue that he should say "professional youtuber", "professional streamer", or "professional content creator" but at the end of the day he is, by definition, a professional
if you just play a lot of nuzlockes in your free time without streaming or making content and still call yourself a "professional" then that's just wrong and cringe, but if nuzlocke-related content creation is a primary source of income, then i don't think it's pathetic or wrong to call yourself a pro nuzlocker