Gotham Knights will not support four-player co-op

The Bat Family only works in pairs, apparently.

Gotham Knights Could Support 4-Player Bat Family Co-op

Gotham Knights Update Adds 4-Player Heroic Assault And 2-Player Showdown Modes Today - Game Informer

Everything You Need to Know About GOTHAM KNIGHTS

Gotham Knights PC Trailer Reveals Advanced Features - KeenGamer

What to know about Gotham Knights crossplay and multiplayer - Polygon

Review, Gotham Knights boasts variety yet lacks impact, Culture

Gotham Knights 2 & 4 Players Co-Op [Explained]

Gotham Knights will get a new 4-player co-op mode after launch

Gotham Knights Confirmed to be Locked to 4K/30fps on Consoles, 4-Player Co- op Mode Coming

Gotham Knights' PlayStation store listing suggests four player functionality