Metal Banjo is the reskin of Banjo and Kazooie in the multiplayer of Banjo-Kazooie:Nuts and Bolts.
How to become Metal Banjo
You become Metal Banjo if you choose "Grunty's Goons" in a team match. This will make your ride green, and Banjo and Kazooie a robot.
Metal Banjo looks like Banjo, but with a metal body, shorts, and backpack and red eyes. His sharktooth necklace is glowing green.
The Metal Kazooie that resides in Metal Banjo's backpack also has a metal body and red eyes. Her wrench's feathers and red screw is now orange.