Traction is a measure of how far a character can slide on the ground, either by shielding an attack or by wavedashing. It is generally considered best for characters to have a moderately low traction, so they can wavedash an optimal distance.
This is a ranking of each character's traction, from least to greatest. 1. Luigi 2. Ice Climbers (Except on ice, where their traction is best) 3. Mewtwo 4. Marth 5. Yoshi 6. Roy 7-9. Dr. Mario/Mario/Mr. Game & Watch (all equivalent) 10. Samus 11. Ness 12. Fox 13. Bowser 14. Falco 15. Young Link 16. Ganondorf 17. Donkey Kong 18-19. Pikachu/Sheik (equivalent) 20-21. Captain Falcon/Kirby (equivalent) 21. Pichu 23. Jigglypuff 24. Link 25-26. Peach/Zelda (equivalent)