When Sony and Marvel agreed to share Spider-Man for the purpose of the Marvel Cinematic Universe, Peter Parker got to join superheroes he never appeared in live-action with before. Outside of appearances in Captain America: Civil War and Avengers: Infinity War, however, Peter's story plays out in high school. His relationships with his fellow teens in Spider-Man: Homecoming are just as compelling as his attempts to save the world with the heroes he idolizes.
If Peter and his classmates were thrown into the world of The Hunger Games, however, Peter would have his work cut out for him. He's not someone who wants to kill his enemies; he would rather wrap them up in a web and leave them for authorities to deal with. The majority of his classmates have no fighting experience, but they are incredibly intelligent, meaning they'd have to do some serious strategizing to attempt to win the game.
Flash
Flash is an incredibly bright kid, but most of his intelligence is devoted to making puns about the classmates he doesn't like in Spider-Man: Homecoming. He's got a lot of bravado, wanting to appear like he can do anything in front of his classmates, and be the first to do it, but that's not entirely true.
Flash is someone who would talk up his skills in the time leading up to actually appearing in the arena. Once there, however, he'd likely be taken out early by a competitor while trying to run for supplies as the games opened. If he managed to get supplies and go on the run, he'd likely be eliminated while trying to hide out.
Betty
Most of what the audience sees of Betty involves her doing the morning announcements in the Spider-Man movies. She's definitely smart and personable, which might help her with the Capitol audience. She isn't, however, one of the teens who ends up in the middle of the action often.
Betty is likely the type of person who would do her best to prepare her strategy for the games while the skill levels of the tributes are assessed. Once in the arena, however, she wouldn't have the skills in place to last long. She would lose her Capitol sponsors as she would slowly stop playing a part for the audience, as she's often seen unable to hold back her sarcasm from her announcements.
Abe
Much like Betty, Abe is bright and personable. He loves to crack jokes as much as he loves to get the right answers, though he doesn't have many lines in the movie. He also seems to stay calm under pressure for the most part. When other teammates falter or hesitate, he doesn't.
Beyond staying calm under pressure during academic competitions (and on a damaged elevator), the movie doesn't tell viewers much about Abe. It's difficult to see how he would do in a violent conflict. Abe would probably put a lot of thought into how to keep himself alive in the arena, but not necessarily into how to eliminate the competition.
Sally
One of the members of the academic decathlon team, Sally rarely appears on screen in the movie despite the team winning their competition. She spends most of her time with her nose stuck in a book.
The only reason Sally ranks as more likely to make it through the games compared to Flash, Betty, and Abe is because Sally seems more likely to keep a low profile. She doesn't rush into situations like Flash or call attention to herself as Betty and Abe do. She could keep a low profile for a long time which increases her chance of survival just a bit.
Liz
Liz has great leadership skills, and she genuinely cares about people. That makes her the kind of person who'd make alliances. She's not someone who is going to get through the games alone.
Unfortunately, Liz is also not the most observant about the people around her. She doesn't realize that her father is a criminal or that the superhero she has a crush on is in her classes. If she's not as observant in the actual arena, she could easily be betrayed by someone she thought was an ally.
Brad
Technically, Brad doesn't appear until Spider-Man: Far From Home. He does, however, make a big impression compared to some of Peter's other classmates. Brad is the kind of person who goes after what he wants and can be incredibly manipulative to do it.
When he and Peter are both interested in Michelle, Brad takes a step too far in taking photos of Peter and lying about just what was happening in them to make him look bad. He'd be more than willing to get people to turn on one another so he could be out of the fight and the last one standing.
Cindy
Initially, Cindy appears to be incredibly anxious. She doesn't react well to finding out that Peter isn't attending the Washington, D.C. competition for the academic decathlon team. Cindy looks like she's on the verge of completely freaking out.
Cindy also, however, demonstrates a pretty keen sense of self-preservation. When the elevator is about to crash at the Washington Monument, she's the first person to climb through the top. She sets aside her fear and anxiety to make sure she lives. That would likely translate to her finding a way to put up a real fight in the arena.
Ned
Ned ranks so high not because of any fighting skills seen in the movie (or its sequel), but because of his intelligence and sheer commitment to doing the right thing. He's one of the few people the audience sees able to keep up with Peter's lightning-fast thinking - and also able to hack into the programming of Peter's Spider-Man suit.
Ned would be smart enough to track the edges of the arena's grid and use it against the other tributes, finding the blind spots of the cameras, and staying out of sight as much as possible. The trouble is that Ned is also a people person. He doesn't do well on his own. He would need allies around - or at least one to bounce ideas off of. Ned would have to choose his ally carefully or that ally might be the person who gets the better of him.
MJ
MJ spends a lot of time in the first movie being observant and sarcastic. She's always there at the edge of the frame cataloging people. Her observations about people are also pretty on point and would give her an edge in making alliances. It's in Spider-Man: Far From Home that the audience really gets a better idea of just how far she'll go to survive.
When MJ and her friends are threatened in an exhibit, she's clearly terrified and has no real fighting skills, but she still picks up a mace and is fully prepared to use it to protect herself. MJ might not be as skilled with a bow as Katniss or as strong as Peeta, but she would be able to hold her own as a result of her sheer determination.
Peter
In terms of skills and determination, no one else makes it out on top. Peter Parker, after all, is your friendly neighborhood Spider-Man. No fight is too big or too small for him. Though he doesn't like to hurt people, he has shown the willingness to when the situation calls for it, activating the "instant kill" in his suit against Thanos' army in Avengers: Endgame.
Though Peter has the skill to win, which is why he lands the top spot, he wouldn't be the victor. Peter is even more selfless than Katniss Everdeen. Katniss only competes in the games to save her sister from fighting, and then is determined to make sure Peeta survives, not herself. Peter would do the same. He would make sure the tribute who wasn't enjoying the glory of performing for the audience, the person who was the most vulnerable, was the one to actually win the fight.