I hate all people who use legendaries online or in a team. Its cheap, and basically cheating, since beat up terrakion is the cheapest one out there, and its hard to take them out without legendary stats. Also anyone who uses drizzle politoed, I don't hate them as much, but still. Along with people who us every single pseudo legendaries on their team, its cheap and not fighting fair. And then those who do that and rage quit after, through all odds, I win. That's just stupid.
That out of the way, my MVP would have to be Porygon2. Not good attacking stats, but its defenses are great, combined with eviolite and recover, and you have something that won't die anything short of a high powered super power/close combat.