I caught Suicune just now. :3 Get this - I bought 75 Dusk Balls thinking that Suicune is going to be bugger all to catch, and guess how many I threw? One. >_o ..
I had brought it down to 1HP carefully with my combination of Feraligatr's weaker move Bite, and my Marowak's False Swipe (which will never knock off the last 1HP), and I put it to sleep courtesy of Victreebell's Sleep Powder. One duskball later it's proven to be the easiest Legendary to catch in my experience so far. Suicune is Bold, with a 25IV in defence and HP, which is good enough especially for only trying once. I feel like sticking with the first one I caught this time.
It's Bold thanks to my Bold natured Synchronize Ralts, of course. Can't leave everything up to fate ^.^