Reflection is a phenomenon wherein one fighter gains control of an opponent's projectile and uses it as their own attack. Most but not all projectiles reverse direction upon being reflected, sending them back to their original users.
To be reflected, a projectile must come into contact with an attack or object that reflects, such as the aptly-named Reflector, Ness's forward smash, or a character wearing a Franklin Badge. Most reflectors increase the damage done by projectiles, as well as the speed at which they travel back, and can also change their remaining active period (lifespan) to further adjust how much effective distance they can cover. Projectiles can be reflected in any direction, and can be reflected multiple times to multiplicatively increase the damage dealt.
In Super Smash Bros. and Super Smash Bros. Melee, if a projectile is too strong for a reflector, the reflector breaks as if it was a shield and stuns the user. From Super Smash Bros. Brawl onward, the projectile simply ignores the reflector and hits the user. In the case of Ness's or Lucas's forward smash, should the overpowered projectile collide with the move's hitbox without striking the user, they undergo a proportionally-substantial amount of lag due to being outprioritized.
Reflectors are generally very useful moves, as they help prevent projectile camping and spamming. As such, characters with reliable reflectors tend to have better matchups against characters that rely upon projectiles, such as Samus, than those who lack a reliable reflector.
In addition to the above, Villager and Isabelle are able to grab projectiles and items and store them for later use via their neutral special move, Pocket. While not strictly a reflector, retrieved projectiles have their damage increased by 1.9×, much like the damage multipliers used by reflectors.
In Super Smash Bros. 4 and Super Smash Bros. Ultimate, projectiles can only be reflected up to 7 times before disappearing. Additionally, in Ultimate, a visual indicator in the form of a flashing blue hexagon (akin to Fox's Reflector) is displayed when a projectile is reflected.
In Spirit Battles, damage dealt by reflected projectiles is increased by the "Reflect-Damage Buffed" rule, often accompanied by the "All fighters' reflected projectiles have increased power" condition.
List of reflectors
Reflectors only available as custom moves are in italics.
List of reflectable attacks
By Assist Trophies
By stage hazards
By enemies and bosses