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)
15. Young Link
17. Donkey Kong