Secret Ninja Attack
In this Final Smash, Greninja sends one or more foes airborne by using Mat Block: hitting them with a tatami, then overwhelms its opponent with slashes, kicks, and palm strikes in front of the moon. Greninja then readies a final blow to meteor smash the foe. It is similar to Ike’s Great Aether.
The Final Smash deals a total of 52% damage: 2% if the opponent(s) are caught by the Mat Block, 5% for the Mat Block flip, 2% for each rapid attack, and 15% for the final blow.
Aside from the initial Mat Block, the attack is visually identical to Zoroark's Fury Swipes attack; however, the Secret Ninja Attack deals significantly more damage, and the final blow cannot be teched (except in Ultimate).
In Super Smash Bros. Ultimate, Greninja transforms into Ash-Greninja for the Final Smash.
Greninja activates this move by striking downward at a tatami, a type of mat, to flip it upward and hit opponents, referencing Mat Block (known in Japan as Tatami Flip), formerly one of its signature moves in the Pokémon games. Mat Block possesses the ability to defend the user's side of the field from all attacks used after it; however, unlike other protective moves, it does not possess increased priority and thus will fail if used last in the turn. It is also only able to be used the first turn after Greninja enters the field; at all other times, it will fail. While not named after it, the move's overall aesthetics may have drawn inspiration from Night Slash, a move Greninja can learn by leveling up in the games.
In the Pokémon anime, upon his final evolution, Ash Ketchum’s Greninja originally obtained a unique ability called Bond Phenomenon, but in the game, Greninja obtains a Bond Phenomenon's true form called Battle Bond. It is similar to Mega Evolution but relies on being in sync with Ash rather than a Mega Stone. This transformation caused Greninja to temporarily take on a design based on Ash and his Kalos outfit, as well as producing a psychic bond with Ash. The transformation later appeared in the main series games with a special Greninja (Ash’s) only obtainable in the Sun and Moon demo, where the transformation would activate upon defeating an opponent. This transformation appears in Secret Ninja Attack in Ultimate.