Well, think of the secret characters...
Dr. Mario, Luigi, Ganondorf, Falco, Young Link, Pichu, Jigglypuff, Mewtwo, Mr. Game-and-Watch, Marth, and Roy.
The "power hitters" are Ganondorf, Roy, and Dr. Mario (enough), and Young Link (enough), and Mewtwo.
The "speed players" are Pichu, Jigglypuff, Falco, and Marth (though still strong).
Mr. Game-and-Watch is a little of both, and is somewhat unpredictable, respectively...
And Luigi is pretty much right in the middle.
Now, you take a slew of experience gamers and have them match these secret characters against each other, the power characters are going to win on a small stage, the speedy characters will probably fair better in more open range.
But a character like, say, Luigi, who is well-rounded, has a chance to win anywhere. He's quick but also has very strong attacks, like his Fire Jump Punch.
In my opinion, Luigi, like Mario, has the greatest chance of winning amongst the other characters, because he's so well-rounded and versatile.
Of course, I'm not biased at all...
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"Word I was in the house alone,
Somehow must have gotten abroad:
Word I was in my life alone.
Word I had no one left but God." -Robert Frost, "Bereft"