Knuckles the Echidna

Knuckles the Echidna (, Knuckles the Echidna) is a character from the series.

Origin
Knuckles first appeared in  and is one of the main characters of the Sonic the Hedgehog series. He is aptly named for both his spiked gloves and immense physical power, only rivaled by Sonic's supersonic speed. He lives alone on Angel Island, the location of an ancient and powerful jewel known as the Master Emerald, which is said to be able to control the power of all seven Chaos Emeralds. Since birth, he has been tasked with guarding the Emerald from potential intruders. He is serious and headstrong, but due to his isolation, very gullible and easy to manipulate. On multiple occasions, Knuckles was tricked by Dr. Eggman into thinking that Sonic was attempting to steal the Master Emerald. Due to this, along with their conflicting personalities, he sometimes clashed with Sonic as a rival. However, upon realizing his mistake, he assisted Sonic in defeating Eggman, and has since become a close ally.

In Ultimate, Knuckles has three abilities as an Assist Trophy. The first is digging into the ground like a drill and then uppercutting back up. Knuckles's ability to dig into surfaces first originated in ' and '; however, in both games he could only dig if he had the Level Up Item Shovel Claw. He could also dig into the ground and then uppercut in . It was not until  that he could dig without the Shovel Claw. The uppercut resembles the Spiral Upper, an ability Knuckles first learned in Sonic Adventure 2, though he does not necessarily need to dig into the ground first before performing it in his own games.

His second ability is the Homing Attack, which also made its debut in Sonic Adventure as a move only Sonic could perform. Knuckles was first able to use it in , though he could only perform it when following Sonic. He could first use it on his own in . His third ability is simply punching the opponent with his fists. Knuckles is often associated with punching in many Sonic games and often has the ability to punch enemies as a part of his moveset in his playable appearances in Sonic games, more specifically the previously mentioned Sonic Adventure and Sonic Adventure 2 as well as in . He is also seen punching, specifically, during his idle animation in ', ', and . His punch-punch-uppercut combo closely resembles a combo he could perform in .

As a background character
Knuckles, like Tails and Silver the Hedgehog, appears running through the shuttle loop in the background of Green Hill Zone.

As a background character
Knuckles reappears as a background character in Green Hill Zone in the 3DS version.

As a costume
Knuckles appeared as a downloadable costume as part of the final wave on February 3, 2016.

Trophy
Knuckles's trophy appears in both versions. In, it is part of the Sonic & Friends Trophy Box.

As an Assist Trophy
Knuckles attacks nearby fighters with his fist. He can also dig into the ground and then attack with an uppercut, so be careful! Knuckles appears in Ultimate as an Assist Trophy. He attacks opponents with Homing Attack, and also digs into the ground and then uses an uppercut to attack. He may also simply punch opponents with his fists. He is also able to be KO'd. He cannot be summoned on Brinstar Depths, Castle Siege, Corneria, Green Hill Zone, Pilotwings, Spirit Train, and Venom.

Like Shadow, all of Knuckles's non-Japanese voice clips are reused from Sonic Generations. Unlike Shadow and Sonic, this extends to Japanese due to being a new Assist Trophy.

As a background character
Knuckles also once again appears as a background element of Green Hill Zone. Because of this appearance, his Assist Trophy will not appear when playing on the stage.

As a costume
The Knuckles costume from the previous game was not in the base game, but was rereleased as DLC on April 17th, 2019. The costume features a slight redesign: its gloves now have fingers, a possible reference to Sonic Boom.

In the trailer, a Mii with the costume is seen headbutting the ground, a possible nod to his digging ability or one of the moves he can perform on a grounded opponent in Sonic the Fighters. He is later seen following Tails and Sonic to a Spring on Mario Circuit, possibly referencing both Sonic Heroes and Team Sonic Racing, a then announced game releasing the month after.

Spirit
Knuckles also appears as an Ace-class primary spirit. He can be summoned using the cores of and.

Trivia

 * The picture of Knuckles with Sonic on Palutena's Temple on the Ultimate website is likely referencing the Sky Sanctuary from Sonic & Knuckles, of which Knuckles is often associated with. The Sky Sanctuary is also where Sonic saved Knuckles in Sonic Generations.
 * The picture of Knuckles on Umbra Clock Tower might also be a reference to the Sonic Adventure 2 level Pumpkin Hill, a similarly somber location that also has a clock tower section, being one of Knuckles' most recognizable levels from that game.
 * Super Smash Bros. Ultimate is the final game where Travis Willingham voices Knuckles, as he was replaced by Dave Mitchell starting in 2019's Team Sonic Racing.
 * Willingham also provides the voice of another third-party Assist Trophy, Guile.

Knuckles