Wait what? Of course he has the main character plothax. ALL MAIN CHARACTERS DO. It doesn't mean that the advantage he gets from being a main character can't be that he's smart.>every situation is written for him to win with his magic negating card
No, every situation is written for him to win by using the M0 in order to trick the opponent in someway and then outwit the opponent. Goddamnit M0 is only effective if he somewhat understands the spell he is up against, so that he can predict what kind of usage of M0 would be best.
Kuzumi wins by using wits. M0 and Lucy are only tools for him to use if he thinks it's a good idea. Note the "think" and "good idea". Meaning that HE'S THINKING. WHEN YOU'RE THINKING IT'S A PLUS IF YOU'RE SMART.