I once caught a shiny Shroomish on Sapphire, and I didn't realize it until about 2 years later when I was releasing some Pokemon that were sitting in my box that I was never going to use again. Now it's a level 72 Breloom on my Fire Red. My other unfortunate shiny encounter was when I was in the Safari Zone in FR. I was joking around with my cousin telling him how I would always find shinies in FR. We both decided to if we could find any of them in the SZ. By the time I had only 1 safari ball and one step left, a shiny Paras appeared. My cousin thought I was joking, but I showed him as I threw my last Safari Ball at it... and no luck :( Now I haven't seen a shiny Pokemon on any game since then...