In simpler terms, this leak states:
Two AT's from Brawl have been made playable.
There is another Mario Newcomer, who will be unlockable.
No newcomers for Zelda - Tingle is an assist.
Ridley is playable. He was hard to design.
Palutena is an AT. She has a forcefield surrounding her that acts as a counter. When you hit her, she fires a beam at you.
Meta Knight and Wolf have been changed, and are very different.
There are no cut characters.
There are two Final Smashes for each character. A low percentage one and a high percentage one. Apparently we see evidence of this in Mega Man's trailer.
There will be costumes for certain characters.
There will be 5 Melee stages and 5 Brawl stages.
Stage Builder has a lot of new options such as texture.
There will be DLC for Stage Builder
Grima (FE:A) is an AT who works similar to Andross
Before E3 we'll get 2 veterans/newcomers per month.
Not much music has been composer for the game. The main theme is hidden in the E3 trailer.
We'll get two newcomers at E3
Hidden newcomers are to be revealed after launch.
We'll know the launch date within the next two months.
So this "leak" is killable by:
No AT from Brawl being playable aside from Little Mac
No other Mario newcomers.
Any newcomer for Zelda, such as Tingle and Ghirahim
Ridley not being playable
Palutena being playable or not in the game at all
Meta Knight and Wolf having the same moves
Any Brawl character being cut
A second Final Smash not being implemented when characters have higher damage
No alternate costumes
More or less than 5 stages from Melee and Brawl being back
No new features for Stage Builder, or no Stage Builder at all
Grima being anything else but an AT, or not in the game
Getting more or less than 2 veterans/newcomers per month until E3
A lot of original music or none at all
More or less than 2 newcomers being revealed in the E3 trailer
Hidden newcomers not getting revealed after launch or no hidden newcomers at all
Launch date not being revealed within the next 2 months
So if Wario, Yoshi and a newcomer are revealed this month this leak will be dead. Oh, Lady Palutena, save us!