Jessica Jones
Any team-up of Marvel’s heroines has to feature the first MCU super-woman to get her own vehicle (Peggy Carter is awesome, but she isn’t super). Beating Captain Marvel to the punch by four years, Netflix’s acclaimed Jessica Jones lifted the character up from a relatively obscure comic book hero into one of the most celebrated women in the Marvel universe.
If she didn’t show up, the team would be missing a key element. As The Defenders has shown, every superhero squad needs a jaded cynic like Jessica to provide a necessary juxtaposition with the more straight-laced heroism from the rest of the group. Ms. Jones would surely have a field day teaming up with so many people in colourful outfits.
Though she’s from the TV sides of things, Jessica is as much a heavyweight as the movie heroines, so she could easily hold her own. She’s super strong, super-durable and she even has the capacity to fly. That’s only used as, in Jessica’s words, “guided falling” on TV, but a big screen budget could allow her to actually take to the skies.