There's no limit to how many heroes you take in a game of Zero Dark, but I tend to find that 3-5 is the sweet spot. Beyond that, and you'll find that some heroes just don't do much because it turns out you don't need their particular skills, and if you're playing co-op, there's a lot of downtime for those who aren't activating their particular hero. It's a lot like an RPG. To have a good game, you need an interesting party, but if the party is unwieldy the game tends to get out of hand and it spoils everyone's fun.
But even if you only have two or three heroes, you can still get more friendly minis on the table by taking allies.
Allies are a special sort of upgrade that adds another character to the X Team. "Character" is a generic term for the main players in your drama. Heroes are the leads, but they can still have a supporting cast. You could even have a single hero and a range of supporting characters alongside him or her. There are three options for allies in the starting line up of the game:
Remotes are synthetic assistants. At their most basic, they are simply an expendable drone that can rush up to objectives and interact with them when it's too dangerous to send a hero: zipping around that unexpected enemy mech, or clambering over an otherwise-unscalable object. But they can be improved with a number of their own upgrades, including adding weapons to them to create a mobile gun platform.
Close Protection Dogs are trained to take on an enemy that gets too close to their principle. Great for helping keep smart but weak heroes alive, CP Dogs can also work with the more lethal type of hero to allow them to take on more than one enemy at once!
Embedded Journalists are both burden and buff for heroes. On the one hand, no one like operating under the scrutiny of the media. But it certainly does help to focus the mind! Heroes who are acting within the line of sight of an emjay get bonuses to their actions, but if the emjay gets killed, that's very much the definition of "bad news".
Allies provide a few things to Zero Dark. The first and, to be honest, most important is the option to put some new and unusual miniatures on the tabletop that you might always have liked but never known what to do with. At its heart, Precinct Omega is about giving you excuses to use the miniatures you love more than the miniatures someone tells you you have to use. But there's no value in minis that look great but don't contribute to the game. All the allies are designed to enhance the natural abilities of the heroes: not powerful on their own, but a force multiplier that can make the difference between success and failure at the right moment.
Next blog (sorry this one was a bit later than planned) will look at some of the other types of upgrade and what they add to your X Team.