Me and my friend were battling in Black 2 and I was using one of these. He stupidly decided to try Draco meteor, me laughing my ass off because Gardevoir is immune to them

To my surprise though, it fucking hit. What the fuck? Why would a fairy type get hit by Draco Meteor? And it's not like it's just the Gardevoir in Kalos are immune, because I trnasferred one to pokemon X and Draco Meteor didn't do a damn thing. What gives? Did the pokemon just DECIDE when it wants to be immune to things?

This my friends is why implementing new types needs to be done with more thought, not just shoehorned in out of nowhere six generations into the series.