Gold was my first pokemon game, and without all of the memories I made playing it I wouldn't be here today.
I couldn't ever beat the Elite 4 as a kid so I would end up just getting frustrated and restarting it. Looking back, I realize I was trying to win with some pretty terrible 'mons.
Anyway in one of the run-throughs I ran into Suicune for the first time (on that file). My first poke wasn't going to be fast enough to damage it, and my best ball was a Great Ball. I had nothing to lose so I threw it. I can still see that little blue ball arcing across the screen, headed straight for that magnificent beast. It opened up and Suicune was inside; I knew it wouldn't last long though. I was expecting it to burst out of my Great Ball and flee, but it just kept shaking in that certain way only a poke ball can. Once, twice, three times. I couldn't believe it. I had captured the Aurora Pokemon. This is hands down my best experience in Gold.
Some honorable mentions are: Climbing Burnt Tower time and time again to catch Ho-oh, finally killing Whitney's Miltank every time, the first time that I caught Lugia, and last but certainly not least, discovering that Lapras was the monster roaring in Union Cave.