Dang, the WTF moments are rolling in faster than ever now! In Challenger Cave, I found a Riolu and only had a few Ultra Balls and one Quick Ball. Fully expecting failure, I chucked the Quick Ball without doing anything to weaken it. My thoughts as it happened:
First bob - It's gonna fail now.
Second - Oh, hey, that's neat.
Third - OK, seriously now.
Click - NO WAY.
I guess it was meant to be.
EDIT:
Same cave, found a Sableye. Got it to red HP, but it broke out of all my Ultra Balls (I only had two). I resigned myself to waste turns to get it so a Timer Ball would work, but not before chucking a Repeat Ball just for sh*ts and giggles. The Repeat Ball catches it. I hadn't owned a Sableye before that. Today has been a series of wins for me.