Mine's an ensemble of characters who have fallen out of their stories into the real world. So, it really depends on the character. But, I'm game...let's take a look and see. I guess I should do this by teams.
Princess Stellaria - she was a combat support mage for the Hero of Prophecy's party in the JRPG she fell out of. In her heyday, she would have just dropped a meteor blast on Dan's head. This, however, is NOT her heyday. Her powers faded into nonexistence a year after she arrived in the real world, and she's now a grad student in quantum physics. This doesn't stop her from remembering what she once was, and all of her instincts are still that of a support mage...so, she's probably try a stupid bluff that nearly gets her killed. She's not beating Dan anytime in this lifetime (but, if Dan happens to like quantum physics, they might get along).
Major Atria Silversword - depends on whether she has her mech or not. If she has her mech, I guess I'd have to ask how Dan happens to feel about volleys of missiles with multiple warheads (Atria is a follower of the "there's no kill like overkill" philosophy). Happily, at the moment she doesn't have her mech, so she'd be relying on her antigrav belt, sabre, and handgun...which happens to fire explosive rounds. And she's a good shot...and she's fast enough to keep up with somebody who can knock bullets out of the air (she comes from an anime). So, I don't think Dan makes it out of this one alive.
Captain Infinite - this is a bad news/good news situation for Dan. The bad news is that Cap is THE superhero (he's an expy of Superman). He's got super strength, he flies, he's bulletproof, and he can shoot lasers from his eyes. The good news is that after WW2, he swore to never again take a life in combat. So, Dan loses, but he'll still be breathing at the end.
The Destroyer - this is a devil king with the power of a god. So, Dan ends up impaled by a spike of whatever the nearest building is made of and pinned to a wall. It's not even a contest.
Jenny Calhoun - she is a monster hunter from a long line of monster hunters. She has superior strength, is fast enough to knock bullets out of the air, and is an expert with her two knives. Jenny vs. a pack of werewolves is an unfair fight...for the werewolves. So, if Dan can keep up with her, he might be able to fight her to a standstill...but I haven't seen Dan dodge any bullets in these samples, so...
Jack Death - he is a rip-off of John Wick (as in, his creators saw the John Wick movies, liked what they saw, and created him to get a piece of that action). So, can Dan beat John Wick? If yes, then he can win. If no, then he's dead - Jack doesn't miss.
EDIT: Oh yes, and if you want to see these teams fight, the first team battle began in today's chapter.