try getting some folks actual friend codes to face em.
basic brawl/with anyone mode is more or less crap nowadays anyhow.
part of the reason yo u probably aren't getting anyone is because its trying to match you up with someone close to your area (i'm assuming, correct me if i'm wrong anyone, but doesnt' basic brawl only work in your region, I.E. if you're from america you'll get american players, if you're from japan you'll get other japanese players.) since the chances of anyone in Brazil still playing brawl are very very very very VERY slim(no offfense dude..) the chances of you finding anyone to play in with anyone mode is slim.
however, don't worry, as there are more than enough people both here, and at other websites willing to face you in friendcode matches. Most of them however won't touch basic brawl either cuz its turned to such crap now.
the only drawback is you're going to have to find folks to play you who are closer to brazil/south america, as facing folks from other countries like the USA, Austraila, Etc, is going to result in HUUUGE lag most of the time, maybe not all the time, but the majority of the time facing someone who isn't as close to where you live, is gonna result in major lag issues.