Now that my second living dex (that I'm planning to transfer to Gen 7 once the Bank is updated) is complete, I'm restarting all of the Gen 6 games. I'm playing the first game out of four, X.
I did prepare in advance: I bred Pokémon for a well-balanced team in each version (I transferred the eggs to the newly started game) and saved all my Lucky Eggs from previous playthroughs.
I won't move my living dex to the cartridge for instant Pokédex completion yet: while there's still stuff to do, Leagues to beat and Legendary Pokémon to catch, I'll act as if I didn't have a living dex and just catch the Pokémon I see.