Team Attack, named Friendly Fire in Super Smash Bros. Melee, is an optional feature for Team Battles appearing in the Smash Bros. games. Normally, teammates are incapable of attacking or damaging each other, with attacks simply passing through them with no effect. Activating Team Attack disables this immunity, allowing teammates to hit or even KO each other.
On the surface, Team Attack has no advantages and is simply a hindrance (for example, teammates must get out of the way of projectiles). However, it does give rise to some new strategies:
The vast majority of tournaments for every game require that Team Attack be turned on. This ensures that teammates cooperate a lot more with each other and ensures that 2v1 strategies aren't as lopsided.
In most one-player modes, Team Attack is turned off so players and enemies cannot hit their teammates.
Some moves and Final Smashes can affect teammates whether Team Attack is on or off. These include:
If Team Attack is enabled, the Team Healer will consider any teammate an enemy, which means it'll either heal them for 11%, or damage them for 8%. Leaving the option turned off does not affect the bonuses Bully, Predator, and Stalker; even though teammates are immune to one's attacks and so the only viable target is the opponent, these single-target-penalizing bonuses still activate in 2-on-1 or 3-on-1 matches.