Ruby and Sapphire is basically like Emerald - its near identical to Fire Red/Leaf Green
Make sure you have the Real Time Clock on on VBA - if you need to change the settings, change them and then close and re open VBA
Basically, the game starts on a random frame on seed 0 on a different frame each time you load the game - seeding in 3rd and 4th gen(dont know about 5th gen) is basically the game starting on a random frame from 1 - 4.29 billion (i dont think its exactly what seeding is, but it is a different way of looking at it).
So basically, to RNG on Ruby and Sapphire, load the game, make a save state, catch a random lengendary and check its IVs, use PokeRNG to find the frame of that legendary in seed 0, if the frame is 50million off your target frame advance frames, if not reset again.
Its much easier than in Emerald, because of the random frame advance, you can reach any frame in a relatively short time. I got method 4 frames for Registeel though, so it can be a bit dodgy.
Hey man, I noticed you were able to abuse on Ruby and Sapphire. I was wondering, how did you do your steps on abusing your legends? Is it the same on Pokemon Emerald? I wanted to ask cause I always get inconsistent frames. I let the clock pass by for 10 seconds after I reset then when I caught the poke, the frame is already at 2 million+. =__=