I just found out today Ruby/Sapphire has shiny Pokemon, and it was a total surprise.
My playtime is almost 200 hours and before today I had never encountered a shiny Pokemon. Then suddenly, bam I run across a shiny Hariyama. Lucky me it doesn't use Whirlwind and I catch it.
I have no idea how shiny Pokemon in Ruby/Sapphire work, but I remember very well that in Gold/Silver shiny Pokemon would have higher offensive stats, and lower defensive stats than the non-shiny version of the same Pokemon.
I used to fanatically use a Gameshark with my Silver/Gold and catch nothing but shiny Pokemon all the time.. and I am positive the shiny versions of Pokemon have higher attack stats and weaker defence stats than the normal versions of Pokemon.
It may or may not be the same in Ruby/Sapphire, I don't know at this point. Ever since my dog ate my Gameshark for my Gameboy Color I haven't bothered to buy a Gameshark for my Gameboy Advance SP.
Hmmm... guess I'll have to start Ruby all over again and use the "save the game then encounter a legendary Pokemon over and over and over again until it randomly spawns as a shiny version of itself" trick.