The Legendary Birds (Pre-Elite Four)
The legendary birds are handled as Method 1 Pokémon, but the PID and IVs for all three of them are created at one time using. Moltres is on frame 1, Zapdos is on frame 6, and Articuno is on frame 11. Please note that all RNG advancement must be done immediately before releasing the birds, as the Nature and IVs are created at that time.
Moltres
Frame: 1
Zapdos
Frame: 6
Articuno
Frame: 11
The Legendary Birds (Post E4)
Once you have beaten the Elite Four you may speak with Professor Oak and he will re-release any birds which have not already been captured. The remaining birds will be regenerated in the same order as they were originally (Moltres, Zapdos, and Articuno). If none were captured they will appear on Frames 1, 6, and 11. If one was captured the remaining birds will appear on Frames 1 and 6. If two were captured the remaining bird will appear on Frame 1.
I have been trying to understand what this is saying, is it possible to capture the legendary birds before beating the elite 4?
I am trying to RNG for the legendary birds, but at least when i talk to professor oak all three are released at once, so i quess i will have to choose one and RNG for that, and not RNG for the other 2, if that is right?
I have beaten the elite 4 once, but not the second time where they have higher levels and stuff, if that is what the OP is reffering to by the Pre and Post elite 4?