[s4e13] The Joining: Part 2 (2027)

Upon arriving at the Watchtower, Batman reveals he had already hacked the League’s systems months prior as a "precaution". If you'd like, I can: Detail the Justice League's powers shown in the show. Compare this version of the Justice League to other series. Provide a summary of the Season 5 follow-up , "Lost Heroes." Which of these The Joining, Part 2 | The Batman (2004) Wiki | Fandom

During the invasion, even Gotham's villains—including The Joker, Penguin, Bane, and Mr. Freeze —fight alongside the GCPD to defend their city.

The episode ends with Batman joining J'onn on the Watchtower space station, where he meets other heroes: Green Lantern, The Flash, Hawkman, and Green Arrow .

Encouraged by Alfred, Batgirl and Robin disobey Batman’s orders to stay behind and join the fight, eventually holding off robots while Batman hacks the system.