The only shiny I've gotten in HGSS other than the obligatory red Gyarados was a shiny Ekans in SoulSilver. I was just minding my business, grinding before going to the Azalea gym and BAM. There it was. I named her Pants and traded her to HeartGold to use there, because I was doing a challenge on SS at the time and Ekans wouldn't fit into it. She's an Arbok now and almost level 60, I think. I need to start RNGing in HGSS though. I find RNG more fun than shiny hunting, and it's a lot less tedious. Plus you get results you want, not like...shiny adamant Abra. Ruh roh.