Gotham Knights

Microtransactions in Gotham Knights are summarized as...

The game features no in-game purchases. There is a DLC pack, which features nothing but skins for in-game characters, as well as some in-game items. This DLC is very expensive at almost half the base game price. This DLC can also be purchased bundled with the base game as a Deluxe edition, which makes it somewhat cheaper.

Has a "deluxe" edition of the game which features (almost) nothing but in-game cosmetic items.
There are no additional purchases other than a "deluxe" version of the game. No microtransactions, no DLC.