How much of the plot and how many of the girls are set in stone right now? My impression is that your outline is quite complete.
There's a lot of stuff that is subject to change: with any big, long-term project like this, you need to be fluid and adaptable, because you're never really sure what will hit until it's out there. For example, we weren't expecting people to be
so on-board with having as much character-based stuff as opposed to just plain flirting or general story events, so we've had to shift a little to make sure we add more of those alongside the story beats. The outline itself is pretty much there, I don't see any major changes to the destinations along the way, and we have the broad view of what we're going to do when we get there. How we get there is a completely different matter, and it may even alter how we approach things down the line.
As for who's going to show up, there's only one confirmed character (Storm) and whoever else we have alongside her. We've gone over every X-Men-adjacent woman (and I do mean
every, I've made some deep pulls that have had the other devs ask if I'm literally making these characters up to make sure they're paying attention) and we've discussed how we'd implement them if they made it into the game. Now, to be clear,
that doesn't mean every character we've discussed will make it in, that's just us doing our due diligence. Some characters may make cameos in backgrounds, maybe they'll have some dialogue, that doesn't mean they're confirmed as main girls. Some characters, let's be honest, if you know the comics, you can probably assume they'll be in there, there's a whole bunch of no-brainers for inclusion and we'd be idiots for not throwing them in.
But.
How we will end up dealing with them, that's an entirely different matter. We've had some serious discussions about how to handle some characters, because, while we love them dearly, it's hard to work out what to do with them to differentiate them from other characters or just to find a compelling hook for them that isn't based on a complex backstory. And then, while we're talking, someone makes a comment, someone else follows up on it and it's off to the races, because we suddenly worked out their entire character arc in five minutes flat. In a lot of ways, we've taken many of these characters back to their roots - X-23 is an excellent example, because, right now in the comics, she's basically Sexy Girl Logan, completely different to any portrayal we've seen of her in the past. The version we're working with is closer to how she was for a long, long time.
All of which is a roundabout way of saying that when you ask if we have all the girls we want for inclusion, it's a soft 'yes' - we have a plan for later characters we really want to include, but it's subject to change based on better ideas, previous scenarios we've written or, sometimes, just something not working the way we want it to. One of the most frustrating parts of being a writer is spending five hours working on something, just to find it's not what you want and it's not playing nice with the stuff you wrote before or after.