EV training doesn't take that long, and even quicker if you use vitamins.
I usually do my level training on Colosseum. (not XD, it's too awkward). After your EV training is done, you should be around L15 or higher, which is perfect to start a full run through Mt Battle. With the Pokemon you are training partnered with something that can take out most enemies in one hit (ie something with Surf, Swift, or if you're training a flying type, Earthquake for example), you can stay ahead of the game and end up around L60 by the time you get to Battle 100. (maybe a bit higher or lower depending on what you are training, but it's usually around L60). Figure in the Lucky Egg (you can get this on Pokemon XD if you don't fancy spending 50 hours catching Chanseys in the Safari Zone), and the usual traded Pokemon bonus (1.5 times normal) and you can breeze through the levels. Usefully, the Pokecoupons you get can get you some decent moves (Ice Beam, Thunderbolt, Flamethrower), and helpful items (Leftovers, Salac/Petaya Berries, Choice Bands), and all for free while you train. You get 6,900 for a full run, and since Leftovers cost only 10,000, they aren't too hard to get after a few runs. Berries are a little more at 15,000.
Also, if you have a Pick Up Pokemon in your party, check it every few levels for Rare Candy. Colosseum Pick Up works the same as Ruby/Sapphire, so the odds of finding an RC isn't too bad.
