The word, Brave, isn't what's used to refer to DQ Hero specifically is what I'm saying. They use the word Yuusha. While yes, it translates to Brave, Smash traditionally uses Japanese names to identify characters (such as Koopa, Robot, Packun, etc). Jack makes sense for Joker because that's Jack Frost's name even in Japanese. Obviously while it wouldn't be unheard of for them to start using English translations as identifiers, it would be a break from their naming convention.
Basically what I'm getting at is if you use, say, "Brave" to refer to something like Sora, or maybe even Bravely Default, that would be more accurate to the way other characters are referred to - because even in Japanese they specifically have references that employ said word directly, while DQ's Hero is never referred to as Brave directly, not even in English.