Onoki

How Onoki joined the Tourney
When he was an adolescent, Ōnoki was tasked with cleaning his village's Stone Monument. As he did so, his grandfather, the First Tsuchikage, came and spoke with him. Ōnoki, who believed that the First was just a cheap old man to have such a simple thing as the symbol of the village, was then told that the stone represented the unmovable will of the shinobi of the village. The First then told Ōnoki that he too possessed that strong will, but would lose it if he didn't face adversities with determination.

As a young man, Ōnoki was a student to the Second Tsuchikage, Mū who passed down to him the secrets of Dust Release techniques. At some time in the past, Ōnoki fought with Madara Uchiha, and is the only living Kage to do so. On one occasion, Madara approached them and declared that despite the alliance between their villages Konoha was to remain the dominant one and anything that Konohagakure requested, Iwagakure was to obey. His knowledge of Madara's power made him wary of him, and was thus surprised that the masked man could really be him. He had also encountered the Second Mizukage, his mentor's rival, and was constantly picked on by the latter.

Later in life, he himself would become a teacher to Deidara, though he often implied that Deidara's ideologies and fighting style annoyed him, he was still proud of him. Eventually, Ōnoki succeeded Mū for the title of Tsuchikage, though he would lose his prized disciple Deidara, who defected from Iwagakure after stealing a kinjutsu. During his reign, in the anime, he endured the hardships of the Third Shinobi World War, watching many of his people die in battle. Eventually, Konohagakure offered a peace treaty from the Third Hokage himself. While the Iwa council was against the treaty, Ōnoki strongly considered accepting it to stop the bloodshed. As Tsuchikage, he hired Akatsuki many times for their services in the past, which he rationalised by his concern over Kumogakure's unwavering militarisation. He has also apparently known and dealt with the Fourth Raikage since he was young. Later in the anime, Ōnoki received an invitation from Konohagakure and Sunagakure to join an impromptu Chūnin Exams they would be hosting together. Arrogantly thinking this was an attempt by the two villages to better gauge Iwagakure's strength for an upcoming fight, Ōnoki quickly turned down the offer, merely replying to the hosts that his village was too busy/

After the Five Kage Summit, Onoki received an invitation for a tournament at his doorstep. Little did he know, he was being target by bounty hunter Erron Black for death.

How to unlock
For both methods, you must fight Onoki at the Hidden Cloud Village. Alternatively, you can avoid clashing with him by wishing for him from Porunga, or purchasing him for 640 Smash Coins in the Smash Store. After defeating Onoki, wishing for him from Porunga, or purchasing him from the Smash Store, the announcer will say "Someone else has joined the Tourney!" after a Smash Ball appears on the lower-right corner of the screen with a message saying "You can now use the Hidden Stone Village's Third Tsuchikage, Onoki of Both Scales!" He will be seen left of Etoile, right of Ranfan, above Zhong Hui and below Maj. Cabot.
 * Complete all Test Your Might Challenges with Kurotsuchi
 * Play 3528 matches

When highlighted
Stands on top of a rock.

After the announcer calls his name
Onoki encases his fists in rocks then blasts dust and says "You… you idiot, who do you think I am!? I am the Tsuchikage, feared as Iwagakure's Onoki of Both Scales!!"

Earth Style: Rock Shuriken (Neutral)
Ōnoki forms and sends huge rocks in the form of large shuriken rotating at the opponent.

Earth Style: Rock Bullet Jutsu (Side)
Ōnoki sends a huge rock at the opponent, causing them to fall back.

Earth Style: Rock-Mat Jutsu (Up)
Onoki flies into the air swinging slabs of rock around him, then sends them dropping onto the opponent.

Earth Style: Stalactite Jutsu (Down)
Onoki unleashes three huge rocks to smash into the opponent, crushing them in the process.

Earth Style: Weighted Boulder Jutsu (Hyper Smash)
Ōnoki lifts and hurls a number of rocks at the opponent.

Particle Style: Atomic Dismantling Jutsu (Final Smash)
Onoki announces "Take that!" and sends a wave of rock pillars forward. If they hit, the opponent is encased in a cage of rocks, then created a dust cube with a sphere located at its centre, between the palms of his hands. He then launches it forward saying "This'll finish you!" The opponent is entrapped, then Onoki detonates the sphere and knocks the opponent away.

Victory Animation

 * 1) Onoki checks his back in midair, then crosses his arms saying "If my back goes out because of this, you're going to pay."
 * 2) *Onoki checks his back in midair, then crosses his arms saying "Feel the power of the Ninja Alliance, Mu." (Mu victories only)
 * 3) Onoki sends three slabs of rock forward and says "I stopped because you were just too pitiful."
 * 4) Onoki forms a particle sphere and says "I bear you no ill will, but I'm going to make you disappear now."

On-Ccreen Appearance
Onoki flies to his starting point and says "Strong confidence in self shows you the right way!"

Trivia

 * Onoki's rival is the Earthrealm mercenary who's aging was slowed down, Erron Black.
 * Onoki shares his English voice actor with Sub-Zero, Cyber Sub-Zero, Wolverine, Taskmaster, Orochimaru, Killer Croc, Gon, Venom, Shizuma Kusanagi, Electivire, Wolfgang Heichel, Grunt, King Shin (in FMV cutscenes), Jim Phelps, Emperor Velo XXVII, Red Skull, Lizard, Dubhe Alpha Siegfried, Kazuma Torisuna, Vilgax, Amon, Bo' Rai Cho and Reptile.
 * Onoki shares his Japanese voice actor with Rain and Moltes. Tomomichi Nishimura once did Akuma in Street Fighter Alpha.
 * Onoki shares his French voice actor with Ernie, Kall-Su and Yoshihiro Shimazu.
 * Onoki shares his German voice actor with Third Raikage A, Wamuu, Mr. Chicken, Akisame Koetsuji, Galacta Knight, Alioth Epsilon Fenrir, the Cat in the Hat, Silver Samurai, the Legendary Capoeira Master, Grand Doomer and Gabriel.
 * Onoki shares his Arabic voice actor with Titanic Tim, Smoker, Buggy the Clown, Galdino, Bugaboom, Brad Wong, Remy, Komodo Joe of the Komodo Bros., the Fourth Kazekage Rasa, Raidou, Shinnok, Shivers, Nigel Charles Ratburn, Narciso Anasui, Vega, Black Shadow, Garuda, the Evil Twins, Tadakatsu Honda, King Kashue, Nenji "Okina" Kashiwazaki, Piccolo, Senkuu, Cronicle Asher (in all his Mobile Suits), Richard Wong and Frieza.
 * Onoki shares his Mandarin Chinese voice actor with Shigure Nakamura.