This is just a topic about the luckiest thing that happened to you across the pokemon games.  Either that or lucky things that happened in all the games, it's really open.

Luckiest thing that happened to me actually happened about a week ago.  I picked my platinum version back up (after about 5 months of not playing it ) and walked out of the city into some grass and Cresselia ended up appearing at very low hp.  Apparently I took it down that low a few months ago and never ended up catching it  Didn't have my Gengar or trapinch with me (it runs away) so I just ended up lobbing an Ultra ball at it and caught it.  It's pretty powerful too, knows Slash and Extrasensory at lvl 50, so needless to say I was very happy about catching it.