Mixvire is so uncommon, I dont even understand how you can carry on about him. He's barely even OU at this point, for you to say that a team is weak to mixvire when you rate is like me saying a team is weak to NastyPlot Slowking when I rate, its just totally a nonfactor in todays metagame. Even so, Electivire is so easy to handle. For instance, you say he OHKOes Metagross, but this isnt really so; then, Gross can either Agility, then outspeed next turn and kill, or just use Earthquake and kill anyway. Even if a team is horribly weak to mixvire, no person in their right mind is going to change but a single member of their team to counter that weakness, because mixvire is practically extinct in OU. Its like getting prepared to kill dinosaurs in todays modern world.