I was about to give up in Sapphire...THen when I started breeding in Emerald I bred 2 of them myself and got a Shiney Groudon by restarting in front of it until I did get it (Works well with stationary Legendaries).
I've gotten a shiny Gloom in FireRed
shiny Nincada in Sapphire (lol 2 shinys in 1)
Hatched shiny Togepi in Emerald
Chained for shiny Shinx in DIamond
Chained for shiny Roselia in Diamond (can't really call it chaining, the first one in the chain was shiny)
Shiny Meditite in Diamond (no chaining)
And I've been trying to chain Larvitar for days. It's broken at around 30 six times.