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I personally don't think EVs should matter when you're playing through the game; if you really want one of your Pokemon to have certain EVs, either box it until you beat the game/have access to a good number of areas or just catch another Pokemon of that species. I mean really, in-game you could have bad EVs, a bad nature, and bad IVs on a Pokemon and, depending on the species and what moves you gave it, it can still be useful.
However, with that said I usually try to get a Pokemon with a nature that works for it, though if it turns out to be neutral or is still one that benefits the same stat, I tend to stick with those. I've gotten lucky, though--in my Japanese White 2, I managed to catch a female Bold Eevee (evolved into Vaporeon) on my first try AND a female Bold Solosis with Magic Guard after about three tries or so (no RNGing on both; I suck at it XD).