I once encounted a Draco Meteor Rayquaza on WiFi and i was like ohh man as my team was just OU with Starmie, Lucario and something else. Lucario got a Swords dance in and he switched out Rayquaza after he Did Draco meteor which killed Starmie and allowed my Lucario to get in the Swords Dance, but then I used Close Combat on the Scizor he had switched in which he then switched back to Rayquaza so it took a resisted +2 Close Combat. When the next turn came around Lucario used a +2 Extreme Speed and killed off the Rayquaza and just killed off what was left easily.
He could have easily got me if he didn't switch and keep using Draco Meteror. Its a good move, but one you have to use well.