The ‘Swiss Army Killer’ achievement
can be unlocked in custom matches using the private or friends only settings. Only two people are needed to start a match.
There are four classes available in the game. They are: Field Medic, Assault, Panther and Sharpshooter. These classes must be unlocked using skill points (one skill point each for a total of four skill points). You will unlock the following achievements by doing this:
The easiest and quickest way to start a custom match is via the game’s menu. Simply use the left or right bumper to navigate to the ‘Ghost War’ menu. From here select ‘Play Custom’. Once you are in the custom game menu, you can use the right bumper to access the game’s settings menu. Create a best of nine round elimination game; this way both players can unlock the achievement in one game.
Start the game. You can change the class that you are using at this time while the game loads. Take turns killing one another whilst changing classes between rounds to unlock the achievement.
If you have any questions or can provide any additional information, please leave a comment. Also, please leave a comment before voting negatively so that I can make any improvements or corrections.