Congrats! So I'm guessing you don't count the Red Gyrados in the Lake of Rage? I remember one of my first shiny Pokemon that I caught legitimately and not on an emulator were Nidoran M, a Spearow that fell out of a tree I Headbutted, and a Delibird all on Crystal during different playthroughs. I have also gotten a Roselia in Trophy Garden which may still be out there as I traded it online for something else. Roselia was nicknamed Sparklez. I also caught Deerling, Purrloin, and one more shiny Pokemon during my first run through Black.