Koopa Klaw is a claw swipe that grabs enemies close to Bowser. It has a pummel and two possible throws as options during the grab, allowing Bowser to have a good deal of control over his opponent. It also hits enemies outside of its grab range, serving as a KO option. This is the only move in the game that can either grab or deal direct damage in the same action, adding some unique options to Bowser's gameplay. Foes are able to use their attack buttons and wiggle their control sticks to escape Bowser's clutches quicker, but if they do not move at all, Bowser can bite the opponent up to eight times, doing 2-3% damage with each bite. The Koopa Klaw has the unique ability of allowing Bowser to grab onto an opponent in midair. If Bowser is holding someone in the move, they can be thrown in two directions: pressing forward on the control stick causes Bowser to slash the enemy upwards, while pressing backwards causes him to hurl the enemy backwards with a large amount of knockback. If he hits his enemies farther away, then his opponents will be sent upward with high vertical knockback.
Koopa Klaw's swipe hitbox comes out on Frame 17, ending on Frame 18. After this, the Grab hitbox comes out for 2 frames. The forward throw has a FAF of 41, and the back throw a FAF of 43. As a result of this, is very possible for Bowser to combo from the forward throw Koopa Klaw provides, usually with up aerial or another Koopa Klaw at lower percentages. This is a large aspect of his advantage state, being able to juggle opponents on a semi-consistent basis, especially fast fallers. The back throw serves as a strong kill option - especially off-stage - and its speed makes it hard to react to. The slash can provide mixup options at low percents as well, although it typically serves as a kill option or safety net for poor spacing. As a result, Koopa Klaw is a centerpiece of Bowser's moveset in Melee.
This special attack is shared by Giga Bowser, although it does have some small issues. The pummel can miss on Yoshi completely, and Pichu if the button is mashed too fast. If played with through hacking, Giga Bowser can also combo from the Koopa Klaw forward throw, with a jump-canceled up smash being very possible. Up tilt is also an option on fast fallers such as Fox. However, it is very possible to self-destruct when using it in the air, unlike with normal Bowser, likely due to Giga Bowser's large hurtbox.
In Super Smash Bros. Brawl onwards, Koopa Klaw is replaced with Flying Slam. The two are rather similar in that they involve Bowser doing a claw slash to grab enemies. In the Subspace Emissary, Flying Slam will deal claw swipe damage instead of serving as a throw, likely as a throwback to Koopa Klaw.
Koopa Klaw has no true origin from the Mario series. While Bowser does have claw and bite attacks in Super Mario RPG: Legend of the Seven Stars and Paper Mario, the two are never combined into one attack nor paired with a grab. However, Koopa Klaw could be based on the first hit of Bowser's Drill Claw attack in Super Mario RPG: Legend of the Seven Stars.