Sorry, I'm not an IGN Insider, but I'll help.
I just so happen to have a section on my website that gives info on Smash Bros. Melee about as fast as the public discovers it.
So in other words, you're hardly gonna get any more info than you are now.
Right now the section is closed, since it's down for updating and maintenance, and it will be back along with all the other new sections on my ''reopening'' on July 1.
And to top it off, there will be a little counter that constantly counts down to the release date of Smash Bros. Melee. That is, as soon as I figure out how to make it also show minutes and seconds.
One thing I can tell you right now is that Pit likely isn't a playable character. Instead, Pit is part of some gallery mode. I'm sure you've heard it before, but these are all the characters seen in the gallery mode so far:
A character that looks like Jetpak
An actual Metroid
Koopa Troopa from the Mario series
Plum from Mario Golf
Dixie from DKC2
Rick from Kirby's Dreamland 2
Pit from Kid Icarus
Mario's racing kart
Raphael the Raven from SMW2: Yoshi's Island
Ridley from the Metroid series (oh yeah!)
White Cat from F-Zero X
Misty from Pokemon
Meta-Knight from Kirby's Super Star
Stanley the Bugman from Donkey Kong 3
King Dedede from the Kirby series
Mach Rider
DK Jr.
Your main character from the NES Excitebike
Waddle-Dee from the Kirby series
Blue Falcon from F-Zero
The main character in Balloon Fighter
The Pokemon Snap vehicle
Andross from SNES Star Fox
Andross from N64 Star Fox
Goomba from the Mario series
Dr. Stewart from F-Zero
King K. Rool from DKC
Mario from Paper Mario (that's right, a 2D figure)
Naspi
The Raven from Paper Mario
Tamagon
Ayumi the school girl
Marin from one of the Zelda games
Disk-Kun, one of those Japan disk drive mascots
That's a lot of known gallery characters! And remember, as soon as the game is released, we'll know the hidden characters within days. After all, Nintendo actually revealed Super Smash Bros.'s hidden characters in its magazine! Talk about spoilers!
To be a Koopa, you must become a Koopa.