*spends 5 minutes figuring out what he just said*
Erm...here it is for FRLG.
39584B19 D80CC66A
CE71B3D3 1F6A85FB
198DF179 5413C867
73ECB8A0 BDD8B251
D5AFFB37 6855972C
73ECB8A0 BDD8B251
DO NOT USE WITH POKEMON MODIFIERS, INCLUDING POKEMON LEVEL MODIFIERS.
Master Code for POKEMON FIRE
72BC6DFB E9CA5465
A47FB2DC 1AF3CA86
Master Code for POKEMON LEAF
72BC6DFB E9CA5465
56671F3A 6F4F4D6B
Use those Master Codes for the code to work. The codes will only work on a rom and a real AR. If you upgraded your GSA into an AR, the codes won't work. If you have no idea what I just said, then you should have nothing to be concerned with.
As for Mew and Deoxys, you can't trade between RS and FRLG until you get Ruby and Sapphire plates....and I'm not even sure if it lets you trade Mew and Deoxys since Nintendo has been using some coding stuff to prevent it from trading to Colosseum or something...but whatever...
All in all. I have no idea.