During the LEGO Batman 3: Beyond Gotham NYCC panel today, it was announced tha Oliver Queen and Team Arrow would be added to the game through DLC called the "Arrow Pack." Characters included are Oliver Queen, Diggle, Felicity Smoak, Helena Bertinelli (Huntress), Slade Wilson, Roy Harper, Sarah Lance (Black Canary), and Malcom Merlyn. In addition to that, the DLC will also include an all new playable mission that takes place inside the world of the CW's Arrow, as well as an exclusive vehicle.
The Arrow will be voiced by Stephen Amell himself. There has been no confimation on the other characters, however we can assume there's a good chance that characters like Slade and Canary will be voiced by whoever provided their performance in the regular game.