I think the story will center around the 5 teams trying to stop the Champion in their own way

Avengers

I think they mostly play it safe and go for the main 4 names

1.Cap

2.Iron Man 

3.Thor (Jane Foster) - I think the Thor statue is a reference to Thor Odinson existing in the universe, but I think they will use Jane Foster Thor as a way of differentiating themselves from MvC, and getting a woman onto the Avengers team. I can see her intro being her picking up Mjolnir and entering a magical girl transformation into Thor.

4.Hulk - He’s one of the biggest faces of Marvel, and I think he’s up there with Spidey and Wolverine as someone who needs to be in the game. Also provides a big body for the game.

Guardians/Outlaws

I feel like saying “Which team will assemble next?” and then having the 4 sketches, mean those characters are all on the same team. Going by this pic https://www.reddit.com/r/MarvelTokon/s/camZXnFJIs they seem to be hinting at Star-Lords symbol and the star of hala.

Not really sure what they are going for with this team. Spider-Man did lead a team called the outlaws, and Star-Lord does have a move called “Elemental Outlaw”. Maybe Star-Lord and Carol show up on Earth to warn them, and team up with Spidey and Ms Marvel? Maybe they go out into space to seek help, and that’s how we get stages for other planets? Spidey, Star-Lord, and Carol have been together in the Life Raft from Secret Wars, so there is precedent for them being together. 

1.Spidey

2.Ms. Marvel

3.Star-Lord -  Has unique dialogue with Spidey and Ms. marvel, so I think he’s teamed up with them. He doesn’t have unique dialogue with any of the other leaders except for Storm, but we know he’s not an X-Men.

4.Captain Marvel - Would be the closest thing to a Dragon Ball character in this game. Could have a Binary install. Plus pairing her with Ms. Marvel makes sense, since she is Carol super fan, which would add a fun dynamic to the story. Carol has also been a member of the Guardians in the comics, so it makes sense that she would show up with Star-Lord to warn them about the threat. Also if the Spider-Man team trailer is only going to announce 1 new character, I feel like it has to be a big character. Honorable mention to Phyla-Vell though.

Marvel Knights

1.Ghost Rider - Robbie Reyes wasn’t a member of the Marvel Knights, but Ghost Rider has been. I don’t think this game is trying to be super accurate with the teams. 

2.Daredevil - I think they will do with him like Storm on the X-Mansion stage, where if you pick him, he will disappear from the window. Plus Daredevil has been a member of the Marvel Knights. They also said they wanted to add characters who haven’t been in a fighting game, and Daredevil fits that criteria, and would be the ninja of this game.

3.Blade - Popular character who has never been in a fighting game. Plus if Black Panther isn’t getting in, then we need another brotha in the game.

4.Cloak & Dagger - Has been a member of the Marvel Knights. Could see them operating similarly to Celica from Blazblue. Also much like Magik, they have become popular because of Rivals, but this game was being developed before Rivals came out, so Cloak & Dagger would have been seen as more of a obscure pick from their perspective when making the choice to add them theoretically. 

The Cabal

1.Doctor Doom

2.Loki - The game needs a pure magic user. Plus he’s never been in a fighting game. Honorable Mention to The Hood.

3.Green Goblin- The Norman Osborn for president posters make me think he’s in the game. Plus he’s never been in a fighting game, and we need a Spider-Man villain.

4.Emma Frost - Was a member of The Cabal in the comics. Would work as a stance character being more of a zoner in her normal form, and more of an armored brawler in her diamond form. Would also act as a substitute for Magneto as the X-Men “antagonist”. 

I think the Champion will be the final boss, and possibly an unlockable 21st character. He would definitely work as a grappler, if he is playable.

Roster Prediction With Explanations and some Pics.