Don't believe I've posted here yet...
Anyway, IVs, EVs and Natures is all for the endgame for me. When going through the game I just nab 6 pokemon I think would be interesting before the second badge and train them all equally. Sometimes if I get a cool gift pokemon or ingame trade, they make it in. Of course, it might take a while before I decide on a steady team; if a pokemon's moveset doesn't get less lame by the time they catch up, I usually stick them in the box.
I catch every pokemon I can until I move on to the next town. I still name all the pokemon I catch, even the ones I don't use and might probably never touch. I usually don't use legends either. I feel like that they're just beginner insurance; ingame anyway.