Well Gyrados, obviously. Aside from that, in Crystal I had a shiny Rhyhorn that I discovered while level-grinding in Victory Road. I had also discovered a shiny Lugia but accidentally KOed it, and when I fought it again, it was normally colored. During one playthrough of emerald my starter (Torchic) turned out to be shiny, and in another run I encountered a shiny Zigzagoon but accidentally KOed it. I never found any shiny Pokemon in generation 4 outside of the legendary beasts from a Gamestop event. In Black I captured a shiny Golduck in the postgame which is in my current team.