Enemy Mine: Web Animation
- Red vs. Blue, as mentioned above, in which the red and blue teams often join up to battle O'Malley, and later the Meta.
- Haloid. When Samus and MC first meet, Samus attacks MC for no good reason and they start a running battle. When more Covenant troops show up, Samus and MC join forces to fight them, including a Back-to-Back Badasses moment.
- Not entirely for no good reason. Neither Samus nor MC recognize the other as human at first, and each presumes the other to be more of the enemy. Once Samus is down to her Zero Suit, MC stops attacking her for more than one reason, and once Samus gets a good look at Nicole through the visor, she stops attacking her as well.
- In episode 9 of Mega Man Dies At The End, Mega Man and Dr. Wily have to work together to escape from the guards.
- In Red vs Blue 3, Red and Blue are about to have their epic showdown when Green comes in and beats them up. The result? Red and Blue perform a Fusion Dance to create Purple, who swiftly kills Green in the span of less than 10 seconds.
- More like Jerkass rather than 'evil', but Dave and Lisa from DSBT InsaniT will help out in battles with the Monster of the Week.
- In the League of Legends cinematic "A Twist of Fate" Garen and Annie fight against Katarina and Tryndamere, until the Baron Nashor shows up. Naturally, they choose to team up against the greater menace.