This is what I found concerning Ruby/Sapphire/FR/LG:
Not without savestates. The RNG for those two reseeds itself every time you restart the game, meaning the starting frame is different every time. You'd have no way of knowing it and if you do figure it out, the minute you reset the game, it'll be another one.
well it has been mentioned that once a sapphire games battery has died its RNG functions like emeralds, except that it starts at a specific seed not 0 like emerald so you would have to catch a pokemon in sapphire, find its IVs input those into rng reporter and check what seed its on.
So I've heard you can do it on an emulator thx to save states, or waiting till the battery has died.
Too bad I was considering trying to RNG my FireRed eventually.