The pic with link smashing Mario off the edge and to the right is definately his 2nd forward smash. His shield is on his back. He doesn't remove his shield when doing his dash attack, or up tilt attacks. I destinctly remember that pose from melee, and since Brawl uses the same engine as Melee, and Link has many of the same moves from Melee, it's safe to say it's the same pose as his forward smash from Melee.
The screen where Mario is diong his up tilt on link and link is going higher with more damage proves nothing about Links weight. You can take the screen while Link is in mid flight at whatever point, meaning he could still have a way to go before he reaches his apex in both shots. It's a screen just to show that characters fly farther with more damage. Besides once characters reach their apex, they enter a 'sprawling' animation (able to recover/jump), not the 'flying' animation that Link is doing in that screen (unable to do anything).
Also, wavedashing is without a doubt, in. In Smash Bros., the physics of the game has a very fluid tone. When you jump, your momentum carries you, when you touch the ground, the momentum makes you slide ever so slightly. When you fall on the ground, your momentum keeps you going for a bit, or makes you stay put depending on how you fell. If you air dodge, and touch the ground, you slide slightly as well, if you are moving in a certain direction. This is the core of wavedashing. You airdodge, into the ground, and your momentum carries you in a direction. If they remove wave dashing, they must remove the momentum effect when you dodge into the ground, detracting from the core feel of the game physics. Dodging into the ground is supposed to make you slide. It's part of the game physics. It is honestly just that simple. Aslo, removing the WD removes competetive Smashing.
IMO, wavedashing provides an edge for skilled players. It seperates n00bs, from people who are really looking to improve their game. It also does not provide that much of an advantage, and slower characters do not use it at all.