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.
Traction ranking
This is a ranking of each character's traction, from greatest to least.
1) Luigi
2) Ice Climbers
3) Mewtwo
4) Marth
5) Yoshi
6) Roy
7-9) Dr. Mario/Mario/Mr. Game & Watch
10) Samus
11) Ness
12) Fox
13) Bowser
14) Falco
15) Young Link
16) Ganondorf
17) DK
18-19) Pikachu/Sheik
20-21) Captain Falcon/Kirby
22) Pichu
23) Jigglypuff
24) Link
25-26) Peach/Zelda