If you play Uncharted 3 Co-op Arena for the first time, you may be confused by the variety of enemies you will encounter, but they actually only represent two enemy types + 1 special enemy which appear in late rounds. These are:

• Weak Enemies
• Armored Enemies
• Brute / Boosted Enemies

Each can be killed in a different way. Some can't even be killed with a melee attack at all or at least not in certain situations. You can read detailed descriptions along with some useful tips on how to spot and kill each enemy type and learn about some exceptions after choosing the enemy type from the menu at the top.

Note - some of these tips are very important and required to pass the Co-op Certification Center test.