Giratina was crazy.
I only had three Pokemon; the other three were low leveled HM slaves. So, I got it down to a very low amount of health with my Luxray, who soon fainted afterward. That was all right because he had served his purpose well. SO, I sent out my bulkier Pokemon, Slowking. I had already managed to use up all of my Ultra Balls, so I was stuck with a Premier ball, a bunch of regular Poke Balls, Nest Balls, Net Balls, and a Master Ball. Sure, I could have just tossed my Master Ball, but I wanted to save it. Moving on, I began to toss all of my regulars. I got multiple three-shakes, and the Premier Ball got a three-shake. But, still, I couldn't catch this thing. Negligence to heal my Slowking and super effective moves killed him off, so it was down to Infernape. All I had was some Nest Balls, and guess the **** what? I caught that stubborn som***** with my first Nest Ball.
Fantastic.
Edit - This just happened. And I obviously also had my Master Ball.