In Melee
Enemies have different functions. They cause damage to any character that makes contact with one. The enemies can be picked up with the Z button and can be thrown at other characters. The character who is hit by a thrown enemy will receive about 30% damage and might die at a low percentage. The character that KO's an enemy will receive extra bonus points for every enemy they KO (The points vary on what enemy is KO). Though, they can appear like regular items if using Action Replay. They are similar to assist trophies in Brawl.
 Enemy List
Below is a list of enemies that come out of containers. These enemies also give a certain number of bonus points depending on which one is KO.
 In Brawl
There are no enemies than can come out from a container (even though Bob-omb is an enemy, it is actually classified into an item) in Brawl. However, in the SSE, enemies can be found anywhere. A list of enemies in Brawl can be found here.
 Other enemies
These are special kind of enemies that appear on certain stages. They don't appear out of containers either. No character is awarded bonus points for killing these enemies, assuming that they can be killed. Some of these enemies can appear like regular items using an Action Replay.