The last 'weapon' I used (or the closest thing to it) was an Aron from Ruby (low level, but hey, what's not to love about a progressive-growth companion-weapon that is immune to poison (and therefore, theoretically, zombie-infections). Also, the last thing I killed with Aron was a Torkoal (or however you spell it). So I get two companions that are also leveling-weapons, one is anti-zombie (and turns into Aggron), and the other prevents negative stat changes (which, I presume, in non-pokemon terms means I never get reduced attack, speed or defense (meaning I never get tired, ever)) and can shoot fire; Win-Win!!!