Weight - measured from heaviest to lightest. Weight measures how far characters get knocked HORIZONTALLY(left to right) and many people didn't know this. This list I tested from the Mushroom Kingdom 2 weight scale. Also someone helped me with this by RATING the weights(Mario = 100, a.k.a. average), which is shown on the far left side. I rechecked his work and found one mistake in it, but I fixed it.

--- 117 --- (1) Bowser
--- 114 --- (2) DK
--- 110 --- (3) Samus
--- 109 --- (4) Ganondorf
--- 108 --- (5) Yoshi
--- 104 --- (6-7) Captain Falcon / Link
--- 100 --- (8-10) Dr. Mario / Luigi / Mario
--- 94 --- (11) Ness
--- 90 --- (12-14) Peach / Sheik / Zelda
--- 88 --- (15) Ice Climbers
--- 87 --- (16) Marth
--- 85 --- (17-19) Mewtwo / Roy / Young Link
--- 80 --- (20-21) Falco / Pikachu
--- 75 --- (22) Fox
--- 70 --- (23) Kirby
--- 60 --- (24-25) Jigglypuff / Mr. Game & Watch 
--- 55 --- (26) Pichu

-also
ALL items(except Fans, which weight nothing at all) have a weight of EXACTLY 1 on this scale(with Mario being 100)
Transforming into metal multiplies your weight by 3.
Transforming into Giant multiplies your weight by 1.6
Transforming into Tiny divides your weight by 1.6 (which is the same as multiplying by 0.625)

to find out how fast a character makes the weight platforms go down, just subtract their weight value by 40. This means that Pichu(55) moves the weight platform exactly 1/2 as fast as Kirby(70) does. Not like this is important or anything.

Credits: Blake Mutschler and Aaron Kurtz(and me of course for fixing the mistakes and adding Misc. related data about it).