If someone is serious about double battles, I advise them to get PBR. The reason being is that, if anything, you get a real look at the more experienced Japanese trainers; they play when it is night in America because of the time difference. They know their stuff most of the time and one just getting into doubles can see real strategies from real people. Yes, there is the occasional n00b who uses Groudon/Mewtwo/Lugia/Ho-oh/Palkia/Rayquaza, but chances are they are either terrible or just don't care.
Just breeze through the colosseum battling part to unlock the outfits, passes, etc, since they aren't really that important anyways. The Japanese and other respected double battlers follow Showdown-esque clauses, and the people who use Ubers aren't good anyways. And if you run into a team that has say 6 Darkrai, you can just give in and find a different match.
And don't hack pokemon. :|