Continuing my previous post, I'm going to move on to a general DC crossover: Justice League: Crisis on Infinite Earths. (yes, I'm aware that Knightfall happened after Crisis on Infinite Earths, but the premise is too good to pass up) Much like Marvel Super Heroes, I'll go with twelve playable characters, though in this case, the boss would be like Apocalypse or Onslaught where they couldn't really be playable.
I'm hoping to have at least one character from most of the five Earths that the story focuses on, though obviously, Earth-1 is going to get most of the focus. Each character would have an alternate darker palette - the Anti-Monitor has shadow people as his minions, so these darker palette swaps would take on that role in the game.
Earth-1: I feel like the inclusion of Superman (1), Batman (2), and Wonder Woman (3) needs no justification. Superman plays a bigger role than the other two, but it's Superman, Batman, and Wonder Woman - when it's a general DC crossover, there's no reason not to include them. The Flash (4) and Supergirl (5) seem like they should be here, given their role in the storyline.
Earth-2: home to the Justice Society, serving as a separate universe where the Golden Age superheroes kept adventuring, or grew old and passed the torch to the next generation. While Earth-2's Superman plays a big role in the story, he's not visually distinct from the main Superman (he's got wrinkles and graying hair, and his S symbol looks slightly different, but that's about it), so I think I'll go with other characters. Power Girl (6) may be an older version of Supergirl, but there would be enough of a difference in terms of their gameplay (with Power Girl being more of a heavy hitter or physical fighter than Supergirl) and appearance to justify it. Doctor Fate (7) is another character from this Earth who's easily recognizable, so I think I'll include him as well.
Earth-S: home to Captain Marvel (currently known as Shazam) before his Earth was merged with the main DC Earth and he became part of the main continuity. Of course, we have to include Captain Marvel (8) in here. (I'm used to calling him Shazam, but he was allowed to be called Captain Marvel for Mortal Kombat vs. DC Universe, so I think he'd be called that here as well)
Earth-4: home to the characters of Charlton Comics, who were the basis for the characters of Watchmen. While the Blue Beetle (9) seems to be hilariously outmatched by every single other character that I've mentioned so far (including Batman), he seems to be the most notable character from this universe. (plus, Marvel vs. Capcom games have given us Hawkeye vs. Shuma-Gorath - accuracy in power levels takes a backseat with this sort of thing)
Earth-X: an alternate universe where Germany won World War 2. Honestly, I have looked through the list of heroes from this universe, but none of them stand out to me - maybe it's my lack of familiarity with the DC universe, but the main hero from that universe who's used in this story (Uncle Sam) doesn't seem particularly interesting, none of the other ones like Phantom Lady or The Ray seem to do much in the story, and I don't think I should shoe-horn one into this line-up just for the sake of having an Earth-X character.
Others: While Green Lantern doesn't play a major role in the storyline, it's a big cosmic adventure story, and the Green Lantern mythos is tied to the backstory of the Monitor and the Anti-Monitor, so including a Green Lantern (10) in the roster of this hypothetical game just makes sense. I'm not sure about what was going on in the main DC universe just before Crisis, but John Stewart seems to be the main Green Lantern at the time (not sure what happened to Hal Jordan) so I'll go with him.
I feel like this line-up is short on villains - I suppose it's inevitable, given how severely I'm limiting myself (infinite Earths and only twelve characters? What was I thinking?!), but I should probably include some. Alex Luthor, the last survivor of Earth-3, plays a major role in the story, but if you're going to include a Luthor in a DC fighting game, it's got to be Lex Luthor (11), the greatest criminal mind of our time! (given the scope of Crisis, a game like this would only be loosely based on the comic - Lex gets a subplot in the story where he teams up with Brainiac to take over the five remaining Earths, and it's a point in time where he has his Kryptonite-powered battle suit, so while it's a relatively minor point in the story, it seems like enough justification to include him)
On the polar opposite end of that spectrum in terms of sheer power, Darkseid (12) plays a major role in the climax of the mini-series, and given how jam-packed this book is when it comes to characters, anything that makes someone stand out could work as justification to include them.
Final Boss: it's the Anti-Monitor, obviously. He'd be a giant, and therefore, not playable - while he can become human-sized, it seems like spectacle would take priority here, and making him an unplayable boss would allow for him to be as cheap as he should be, considering how much it took to take him down.
The plot of the game seems pretty straight-forward - the Anti-Monitor wants to destroy all of the positive matter universes with a wall of anti-matter, and the playable characters want to stop him. (The heroes because it's the right thing to do; Darkseid and Luthor because they can't get what they want if the multiverse is destroyed)
TL;DR:
1. Superman
2. Batman
3. Wonder Woman
4. The Flash (Barry Allen)
5. Green Lantern (John Stewart)
6. Supergirl
7. Power Girl
8. Doctor Fate
9. Captain Marvel/Shazam
10. Blue Beetle (Ted Kord)
11. Lex Luthor
12. Darkseid
FINAL BOSS: Anti-Monitor