Greninja (ゲッコウガ, Gekkouga) is a fictional creature from the Pokémon series. It debuted in the series' sixth generation as the final stage Water-type starter Pokémon of Kalos, and represents that generation as a playable character in Super Smash Bros. 4 and Super Smash Bros. Ultimate.
Greninja, a dual Water/Dark-type Pokémon, is a bipedal frog-like creature that greatly resembles a ninja; it wraps its long tongue around its mouth in emulation of a scarf. It is the final evolved form of the Kalosian starter Pokémon Froakie, evolving from the intermediate Frogadier from level 36 onward. It is categorized within the Pokédex at #658 as the "Ninja Pokémon".
According to the Pokédex and based on its statistics in the Pokémon games, Greninja is extremely fast, to the point that it has the highest raw speed statistic of any starter Pokémon (not counting Mega Evolution). Fittingly, it relies on this speed in battle to confound its prey with swift, ninja-like grace before striking with its Water Shuriken move, which is said to be able to shear metal. In exchange, however, it is rather frail because of its low defenses.
In the Pokémon games, Greninja has access to numerous unique abilities. Initially, it was the only Pokémon able to learn Water Shuriken—which it uses in Super Smash Bros.—and Mat Block (used in Smash during Secret Ninja Attack), where it flips a tatami mat in front of itself to shield itself and its allies from incoming attacks. Besides these two unique moves, it has access to a diverse range of offensive and status moves; while its standard ability is, as every Water type starter Pokémon, Torrent, its Hidden Ability is the rare Protean, which changes its type to match each move it uses and ensures it gets the maximum possible power out of every attack, allowing it to take advantage from its large range of available moves.
In Pokémon Sun and Moon, Greninja appears as a gift Pokémon obtainable via the games' demo version. This Greninja has the unique Battle Bond ability, which allows it to transform into its more powerful "Ash-Greninja" form, which initially debuted in the Pokémon anime. In Sun and Moon, “Ash-Greninja” can only be used by male Greninja, and cannot breed.
Greninja has made multiple appearances in the Pokémon anime, but is most notable for being Ash Ketchum's ace Pokémon during the XY series. Having been part of Ash's party ever since Ash received it from Professor Sycamore, the Pokémon developed a close bond with Ash throughout the series as it trained and evolved, eventually gaining access to its strengthened "Ash-Greninja" form because of the connection between Pokémon and Trainer.
With the help of Greninja and the rest of his Pokémon team, Ash was able to achieve his greatest success in a Pokémon League tournament up to that point, only losing in the finals due to Greninja being overwhelmed and defeated by Alain's Charizard. At the end of the series, Greninja bade farewell to Ash, parting ways in order to help protect Kalos alongside two Zygarde, Squishy and Z2.
As a playable character
Main article: Greninja (SSB4)
Greninja debuts as a newcomer in Super Smash Bros. 4. It was first revealed in the Super Smash Bros. Direct on April 8, 2014, alongside fellow Pokémon representative Charizard. Much like in its home series, Greninja is very quick and mobile, similarly to Sheik and Sonic. However, it possesses more consistent KO power overall in comparison to them. It also possesses special moves that can catch opponents off-guard, such as Shadow Sneak and Substitute.
Masahiro Sakurai decided to add Greninja to Super Smash Bros. 4 long before the release of Pokémon X and Y, having initially reserved a space on the roster for a brand new Pokémon. Sakurai's only source material for designing the character was concept art of Greninja.
Greninja is currently ranked 26th out of 55 on the tier list, placing it in the C tier. Greninja's strengths include very fast overall mobility and great combo potential, most notably with its neutral attack's jab cancel, and its up and down tilts. Water Shuriken also grants it a decent projectile, which not only has fairly good travel distance, but is also capable of being thrown out for a fast attack or charged up for greater power. Despite these positives, Greninja has a few noticeable negatives. It has unusually high ending lag in its moveset, especially its smash attacks. Substitute is a weak and avoidable counterattack. Lastly, its grab game is burdened with an abysmal pummel, an overall low damage output, and only two throws whose utility is decent at best. Regardless of these issues, as well as being noticeably nerfed in update 1.0.4, Greninja is still viewed as a viable choice for competitive play, thanks to it achieving decent results.
As a playable character
Main article: Greninja (SSBU)
Greninja returns as a playable character in Super Smash Bros. Ultimate. Unlike in SSB4, it is an unlockable character instead of a starter. Two of the most notable changes are that its water katanas have been replaced with water kunais, and that its Final Smash now features its Ash-Greninja form introduced in the anime and featured in Pokémon Sun and Moon.
Greninja has been greatly buffed from Smash 4 to Ultimate. As with all other characters in the game, its already quick mobility is faster like most characters, while its previously situational moves (such as dash attack, down smash and Water Shuriken) are much more versatile. Due to the game's universal changes to dash mechanics, Greninja can also further exploit its amazing ground mobility, allowing for easier setups into its combo starters, such as down tilt and dash attack. Furthermore, the reduced landing lag on Greninja's aerial attacks gives it an easier time landing, while the universal 3-frame jumpsquat improves Greninja's ground-to-air potential. Overall Greninja retains its status as a viable character in Ultimate's early meta with above average representation as of late thanks to Stroder, Lea, Jw, Somé, and iStudying and is considered as a high or even top tier character by many professional players.