[ORAS] How to start filling National Dex?

[jouzea]

Well I'm far from completing the dex (I'm still at 454) but I'm not in a rush to complete it. What I want is to have a living competitive dex with all Pokemons bred/caught, and trained by myself (Got no idea how to do it on legendaries though). What i do is I breed the egg moves, IVs, nature then wondertrade all of the breedjects. Then from the haul, i release all the common mons. And keep mons that i can use for breeding.