Separating them from their own realities/unrealities/whatevers, of course.
Mario is a lovable idiot that jumps into action before thinking - Luigi follows close behind but is a sissy and prefers to tag along than fight things out. Peach is a "queen bee" among the Brawl ladies and Bowser is a "head honcho" among baddies.
DK and Diddy are blood brothers and totally-hetero life partners. DK is the big, strong, silent type, while Diddy is the short trash-talker.
Yoshi is that mellow guy that just kinda rests unless someone's doing something then he's like "can I come, too?" and the someone is like "yeah, sure, whatever" and they have adventures.
Wario is a fat, obnoxious, perverted jerk-hole that hangs around everyone else and makes the entire cast uncomfortable.
Link is an oblivious, hormonally imbalanced teenager and Toon Link is his audacious younger sibling that makes interaction with other people awkward on a number of levels. Zelda is a reserved, somewhat haughty girl, and Ganondorf is a bumbling thief that takes himself far too seriously.
Samus is an angry single mature woman and she takes out her rage by drinking heavily and shooting nearby people. She feels as if men don't like her because she's ugly but it's really because she's always shooting them and generally people don't enjoy this.
Pit is a noob and naive and everyone takes advantage of him and makes him do laundry and stuff.
The Ice Climbers don't speak English and being around them is very confusing but they're cute so no one really minds.
R.O.B. is the subject of everyone's abuse and he cried to himself in order to redirect the pain because he really wants friends but no one likes him
Kirby is... well, Kirby. Meta Knight is Kirby's keeper and they always hang out making Kirby the dumb one who gets the more intelligent Meta Knight into wacky hijinks. Dedede is a jerkwad that want to smash them both and also a loser among villains because he always loses their group poker games.
Olimar is always followed by a million Pikmin who mercilessly murder anyone who offends him or them. Pichu? Roy? Mewtwo? Now you know. Olimar is unaware of this, though, and dotes on them like babies.
Fox, Falco, and Wolf are a gang-type thing that ride around and generally cause trouble but they also fight crime so people begrudgingly accept their existance. Fox is the ringleader, Falco is the smooth-talker, and Wolf is the angry one who wants to be the leader but has to settle for being extremely badass.
CAPTAIN FALCON LIKES TO FALCON PUNCH AND HAVE SEX WITH ALL THE LADIES! HE'S LIKE DUFFMAN, WITHOUT THE BEER! OH YEAH!
Pikachu is a cute little cutey that is easily angered and almost bipolar. If he likes you he gets cuddly and warm but otherwise he tried to gut you. This brings him into conflict with Pokemon Trainer who wants to catch them all but is thwarted easily because he sucks and is a little dude. Squirtle likes him, Ivysaur is lazy and doesn't care, Charizard thinks he sucks because he does. Lucario just meditates all the time and no one pays attention to him but he sometimes says smart stuff that helps people. Jigglypuff hopelessly pines for Kirby but his oblivious pinkness does not understand the concept of love so she slaps him and then feels bad but it's alright because he's cool like that.
Marth and Ike are like cops with Marth being the experienced older partner and Ike as his younger partner that always flubs stuff up and Marth is tired of him but it's alright because Ike is learning and someday they'll be best of friend and maybe they're gay who knows.
Ness and Lucas are like siblings and like a smaller, less extreme Mario and Luigi pair. Ness is a good-hearted - but thick-headed - leader, while Lucas is the reluctant follower.
Mr. Game & Watch appears out of nowhere, makes a lot of loud and incomprehensible noises, then disappears again, causing a lot of awkward silence to follow.
Snake is a pervert that talks to himself and hides in boxes. But girls like him because he's gruff and manly and smexy. He also smokes and smells bad but girls like that too. Sonic tries to fit in by being cool but no one likes him and he'll run in and be like "YO WAZZUP EVER'BODY!" and they just kind of stare at him and he slinks away. Poor Sonic.
...
It's 1:00 AM and I just spend the past hour watching SSBB fan-video-AMV-opening things and reading Awkward Zombie and Brawl in the Family comics.