Wesker, since he has basically been turned into a crazy kung-fu master in Resident Evil 5 already.

LUKE CAGE

I'm happy so far with the cast of characters announced, but I'm gonna list some characters that will probably not make it in. But just to get REALLY crazy...
 

Marvel

Capcom

" @AgentJ: I definitely agree, Belmont would be awesome, but I'd like to have Solid Snake and Samurai Pizza Cats from Tatsunoko since they didn't make it into TvC! "

 I would like to see these characters in the roster:
Marvel
 Deadpool
Ghost Rider
Thor
Punisher
 
Capcom
Dante
Frank West
Servbot
B.B.Hood 

Deadpool, Dante, Nightcrawler, Phoenix Wright, Captain America, Carnage. That is all.

It better have Gambit I gotta be able to kinetic Card and Cajun Strike assholes.

Marvel - Thor, Deadpool, Moonknight, Black Panther, War Machine
Capcom - Protoman, Frank West, Dante

Young Dante (From DMC3) 
Mega Man (8-bit, fully pixelated Mega Man; none of this Legends BS) 
Roll (You can't defeat the almighty Roll class) 
Dr. Wily 
 
Red Hulk 
Thor 
 
That's all I can think of

Mike Hagger (Final Fight)
Nathan "Rad" Spencer (Bionic Commando)
Guy (Final Fight)
Super Joe (Commando) 
Strider (Strider) 
That dog from Okami :-) 
 
... and Wiki from Zack and Wiki - just so I can kill him.

• Lei Lei

Dante, Frank West, Amaterasu, Viewtiful Joe, Phoenix Wright, Zero, Gene, Deadpool, Maphisto, Moon Knight, Daredevil, Carnage, Punisher, Black Widow, and some Power Stone characters would be great.
 
As far as returning characters go, these are the most important for me:
 
Gambit, Spider-Man, Servbot, Venom, Strider, B.B. Hood, Doom, Rogue, War Machine, Hayato. If they are going to cut characters, I wouldn't mind seeing less from X-Men and SF.

my ideal roster would be ALL of mvc2 with some new marvel faces like deadpool and nightcrawler with more darkstalkers

Carnage
Deadpool
Zero
Everyone from MVC2.

Dudley, Yun, Elena, Dante(DMC4), Gene, Amaterasu, Juri, Gouken, Seth, Gill, Jedah, Lei-Lei, Viewtiful Joe, Squirrel Girl, Deadpool, Blade, Nightcrawler, and Phoenix Wright.

From Marvel: Toxin, Mr. Fantastic, and Deadpool
From Capcom: Viewtiful Joe, Dante, and a zombie with a chainsaw.

Gene from God Hand, The Mega Twins, Mike Haggar, anyone from Power Stone, Phoenix Wright, Zack and Wiki...

If they have Deadpool do this, instant Day 1 buy for me.

I would love to see the Sentry/The Void as the final boss. But as far as playable characters I was really hoping for Leon Kennedy but I think he might be out now that Chris is in. I'd also love to see a bonus stage where you fight Multiple Man and the goal is just to see how many of his copies you can beat up in a time limit (think the car stage in street fighter)

I know who I absolutely wouldn't want to see: Phoenix Wright.  I'm seeing him being suggested by people all over the place and I can't understand why.  He's an effing lawyer!  He's not a fighter in any way, shape or form!  He would stick out like a sore thumb with all the other characters.  I love the Phoenix Wright games, but this wouldn't do at all.  At all!

I'm not much of a fan of fighting games, but if this has Gambit and Deadpool, I'm sold.  X-Men Legends II got me hooked on those characters, so that it doesn't matter what kind of game it is, so long as I can play as them, I want it.

The two companies have so many good characters. I don't know exactly my ideal roster list, but crazy Capcom characters like Viewfull Joe and Phoenix Wright (using "objection!" and "hold it!" as powers like the producer of Tatsunoko vs. Capcom said in a interview) are certain a good choice.
Oh c'mon people, do you really want to see Deadpool? I'm tired of Deadpool, and you?

Definitely E. Honda this time around. Mega Man of course, although I should expect him right? Also, Super Joe!

Gambit...Please just keep Gambit in there.

1. Punisher
2. DeadPool
3. Carnage
4. Stan Lee
5. Spider Carnage

Mahvel: Deadpool, Spider Woman, Hawkeye and Ms. Marvel (Sooo not gonna happen...)
 
Capcom: Wesker, E. Honda, Cammy and especially Tofu

Viewtiful Joe. 
 
Thanos.
 
/thread.

" Barry Burton... that is all. "

Sugarman

Iron Patriot please!

Sugarman!

One word, wait for it.......Nemesis! Proto man would be cool to. On Marvel side I would love to see Ghost Rider and Punisher in the mix.

 Zero, Iron Patriot,   Viewtiful Joe, Silver Surfer, Darkwing  Duck and Jean Reno

" I wonder if this would pretty much be Tatsunoko vs Capcom but Marvel on PS3 and Xbox 360 "

B.B Hood, Viewtiful Joe and Machine Man (Marvel super hero)

Hit-Girl, Hit-Girl, and also Hit-Girl.

The motherfuckin Batman. He don't care it's Marvel vs Capcom, the Batman goes where he wants and beats up who he wants.

Anyone for Speedball/Penance? 

" Hit-Girl, Hit-Girl, and also Hit-Girl. "

Chuck Greene, Gene Godhand and Deadpool.

" @JJOR64: There's no MVC3 board because the game isn't official yet.   But, of course all the returning characters from MVC2.   Add in:  Wesker (RE5) Dante (DMC) Deadpool  Thorany capcom characters they had in TVC  and since they actually made big screen characters viable in TVC, bring in a playable version of apocalypse, or onslaught. They don't even have to look the same since those boss versions were never meant to be played.  "

" Deadpool is a must.  I think they need to represent the SFIV series somehow, but I'm not sure which character would fit the role. I supposed the most obvious choice would be C.Viper, but I was never fond of her.  "

Phoenix Wright!

Doctor Strange 
Daredevil 
Iron Fist 
Thor 
Fantastic Four 
Amaterasu

From the Capcom side: Albert Wesker, Nemesis, Mr.X, Leon Kennedy, Dante, Akuma  H.U.N.K and Barry Burton. From the Marvel side: Spiderman, Venom, Terror inc., Deadpool, Punisher, Rulk, Ghost rider, Vengeance, Red skull, Sandman, Hydro-man and Juggernaut.

Was watching the ECT2 stream on Saturday and they said that Dr. Wily and Nero is in the game.