Here are the ratings for the characters in SSB.
Strength was determined by the character's Normal, Air, and Dash attacks.
Defense was determined by the damage it took for them to be smashed out of the arena.
Speed was determined by a character's agility to move and attack.
The strength of a character's smash attack determined the rating for the Smash Attack category.
The strength (and partly effectiveness) of a character's special attack determined the rating for the Special Attack category.
The sum of the scores (Strength, Defense, Speed, Smash Attack, and Special Attack) determined the Total.
Finally, Score was determined by a character's effectiveness in battle (as you can see, Kirby had terrible stats but he has one of the best Scores).
Character Ratings scores were determined by Bozorgmehr after many hours of intense fighting and analysis.
If you happen to disagree with these scores, then voice your opinion to the webmaster at webmaster@smashbros.planets.gamespy.com.
Abbreviations:
STR - strength DEF - defense SPD - speed SMA - smash attack SPE - special attack TO - total OS - overall score