Its hard to tell with Samus because her jumps are floaty and she has a slow fall speed (since fall speed is not the same as weight in this game). She has some knockback resistance as all heavyweights do, so its harder to send her flying than someone thats middleweight like Mario, or Marth.

Its just Samus though, Zero Suit Samus is a middleweight i believe.

Zamus is quite light if I remember correctly, actually.

Up-special: His big tongue that he always seems to show-off would shoot out, grabbing-then-throwing opponents. It would also act as a tether.
Down-special: Teleports a short distance in the direction of the control stick's direction, then deals damage. Doesn't leave him in a helpless state, but it can only be used in-air once. The attack part is similar to Meta Knight's Down-special.
Side-special: While darting forward, he spins rapidly, dealing damage. Leaves him in a helpless state.
Neutral-special: A chargeable blue fireball. Don't forget that he could breathe fire in Super Mario 64 DS.
Final Smash: This one took me a while to think of, but he would eat one of those Chili Peppers from Super Mario Sunshine that he used in the boss battle with him. His entire body is now engulfed in blue flames. All of his moves have some sort of fiery effect, and his neutral special is extra powerful. This is somewhat similar to R.O.B.'s Final Smash, except with blue flames, and not lazers.
I'm not sure about his smashes and tilts and whatnot. His tongue would probably play a big role, though. He would also float around like Kirby.
Taunts (in no specific order):
1) His victory pose from Double Dash. He basically "licks" the air, twice in this case.
2) The thing he does upon arriving at the home plate in Mario Superstar Baseball. He looks at the camera and sticks his tongue out, while having a creepy smile on his face.
3) Instead of a handstand, he does a "tongue"stand.
Also, anytime he dodges an attack, he turns invisible for a split second, similar to Black Mage's dodge.

I can confirm this. She is plenty light.

She's light? I hope they change that in SSB4. It just...doesn't seem natural. Of course, it is a Smash Bros. game.

I think she should be medium-light. Despite the fact she is fit and skinny, it doesn't change the fact she's a human being.

Okay, how about the fact that she's basically half-bird? Although I do agree with you.

So is Snake, but he's heavy as s***.

Come to think of it, Link is relatively human-ish as well but he's also heavy.

Ike is also human, being human doesnt make you fit to be a lightweight...

Link, Ike and Snake all have a tonne of weaponry in their inventories though (not so much Ike but that sword is huge).
Almost all of samus' inventory was in her suit.

Except that crappy emergency pistol. Thank God she upgraded that stupid piece of crap before Brawl (referring to Metroid Zero Mission).

Still, the majority of "human" characters still fit into middle/heavy class, Mario is middleweight for instance, so is Luigi despite being a leaner character than Mario.

The only lightweight human characters in Brawl are Peach, Zelda, Zamus, Toon Link, and Ice Climbers.

Wait, Olimar isn't considered a lightweight?

Olimar isnt human.

Okay, fair enough

Wow, I learn something new everyday.