My top two choices for Characters in Brawl are the following:
Louie, from Pikmin 2 & Rayman, from Raving Rabbids/Rayman Series.
Nintendo Characters:
Louie (Pikmin 2)
Final Smash: Titan Dweevil - The Titan Dweevil comes up out of the ground, and
it takes out its' four weapons: Monster Pump, Shock Therapist, Flare Cannon, and Comedy Bomb. For each weapon, the element it's based off of, is spread across the field of battle, causing insane damage, similar to the Bulborbs that appear after Olimar lifts off in his Final Smash. Also, it's constantly walking, which causes a bit of damage if the legs are close to the opponents on the field. This would make Louie almost a carbon copy of Olimar, but his FS being different would be awesome. I wish Louie made it into Brawl... >_>
3rd Party Characters:
Rayman (Raving Rabbids Series/Rayman Games)
Final Smash: Bunny Boogie - Yes... Rayman can KO you by dancing... Rayman stands dead center of the stage, and snaps his fingers. By doing this, he changes his costume into a Dancing Uniform (It would vary depending on the song), and the Rabbids pop up, seemingly from nowhere... They all start grooving to the beat, and cause decent damage to the other fighters who get in their way... Warning !!! - If you mess up the Rabbids' dance steps, they'll act as Piplup does from the Pokeball, and run you over the edge, even if you're in the air !!! I would've loved to see some more humor in Brawl. Wario is great, but a simple fart just isn't enough to satisfy my preference for comedic genius... Not to mention, Rayman would be one of the most unique characters in Brawl, had he been on the roster... Oh well...