The Grapple Beam is the name of Samus's extended grab in all three installments of Super Smash Bros. It is a bright blue energy beam that grabs onto opponents and reels them in so Samus can attack them up close, but when it misses, Samus is left vulnerable. It is acquired in almost every Metroid game. When not acquired in a game, it is normally replaced with the Power Grip, allowing Samus to grab ledges. The ledge grab takes on a very important role in the Super Smash Bros. series. The use of the Grapple Beam in Metroid games to attach to certain Grapple points is similar to its special ability in Melee and Brawl of attaching to a ledge from afar (known as a Wall-grapple in Melee and a Tether Recovery in Brawl).
In Super Smash Bros., the Grapple Beam is Samus's extended grab. This allows her to grab from a good distance, and throw opponents very far with this electrically charged beam. However, it cannot be used in midair, which limits Samus' horizontal recovery, and missing with the grab leaves Samus open to attacks for two seconds.
In Super Smash Bros. Melee, the Grapple Beam can be used in midair, not only to damage opponents, but to perform a Wall-grapple. However, midair use of this attack results in Samus becoming helpless. In the NTSC version of Melee, it is possible to extend the length of Samus' Grapple Beam grab by using the Extender trick.
In Super Smash Bros. Brawl, the Grapple Beam can still be used to damage opponents in midair, but now the Grapple Beam's Wall-grapple ability was replaced with the ability to perform a long-range Tether Recovery. This gives Samus an advantage since she can recover from afar. On the ground, however, the Grapple Beam is very slow and laggy. Missing with the Grapple Beam while standing or even while pivoting can result in lag lasting well over one second, which is easily punished. However, using the grab during a dash significantly reduces the lag, which may surprise some opponents due to the Grapple Beam's usually long lag. The Grapple Beam played a cameo role in the Subspace Emissary, as Samus used it to try to pull a R.O.B. from a Subspace Bomb when Ganondorf ordered the R.O.B. Squad to detonate all of the remaining Subspace Bombs.