My first shiny Pokemon was a shiny Rattata in the original Crystal version. Bad news? It was at the very beginning of the game when I had no Pokeballs. To add insult to injury, it was the very first grass patch I walked into. I saved a video on my phone, but nobody wants to hear me ranting at my TV (it was a ROM being played on my modded xbox with an emulator. I'm that crazy, yes.)
Since then I've cheated for some shinies, but I've successfully RNG-ed in Emerald for a shiny Torchic starter (now a Blaziken), Rayquaza, Beldum, Lileep, Anorith, and Deoxys, and I'm going for Groudon, Kyogre, Mew, Sudowoodo and Southern Island Latios shinies. Actually, if anyone wants, I can put up the PKM files sometime this week. They all have the same ivs and nature because they were caught on the same frame (my first shiny frame in Emerald is at 34.56 seconds, Naughty nature and 30 sp attack iv plus some other decent ivs). Yes, I cheated for the Eon Ticket, Old Sea Map, Aurora Ticket, and Mystic Ticket, but hey, the pokemon themselves are legit. (No shiny Lugia and Ho-oh because I cheated for them shiny in FR.)
And my only truly random shiny in Gen III/IV was an Electrode in Cerulean Cave in Fire Red. I hate Explosion.
/long winded comment
EDIT: and yes, I'm new here. Hi everyone!