In Gears of War: Judgement for the Xbox 360, Young Marcus is available as a DLC character that you can use in Multiplayer matches.
There is a catch though, since Young Marcus was only available as a pr-order bonus from Gamestop.
If you still want to get Young Marcus however you’re in luck, because people sell their DLC codes on Ebay.
Check out my other guide if you’re looking for the full list of unlockable multiplayer characters, including exclusive DLC characters, or a complete list of cheats, unlockables, tips, guides, and more.