Hadoken

Hadoken (波動拳, Surge Fist) is Ryu's and Evil Ryu's neutral special move in Super Smash Bros. Crusade.

Ryu
When the special button is pressed, Ryu thrusts his hands forward to release a blue fireball from his hands that deals low damage and knockback. The projectile is rather slow, so Ryu must be careful when using it, as it can be easily dodged, or, due to its low priority, destroyed. However, the move is fairly spammable, and it allows Ryu to have multiple Hadokens on the stage at once.

Shakunetsu Hadoken (EX input)
If the player inputs a direction Ryu is facing immediately after the move starts, Ryu will instead perform Shakunetsu Hadoken (灼熱波動拳, Scorching Heat Surge Fist). This move has Ryu utter "Shakunetsu!" as he releases a bright yellow Hadoken from his hands. This Hadoken is much faster than the normal variant, and hits five times with 2% flame damage each hit, for a total of 10% damage.

Evil Ryu
Evil Ryu's version of Hadoken works the exact same way as Ryu's Hadoken, but it launches at a downward angle in midair. In addition, Evil Ryu's Shakunetsu Hadoken only hits twice, though it deals the same damage as his normal self's, and the midair input releases two normal Hadoken projectiles.

Origin
The Hadoken (sometimes spelled Hadouken) is a very common and iconic attack from the Street Fighter games available to many characters in the series, though it is mostly associated with Ryu and his best friend, Ken Masters. Colloquially known as the "fireball", it involves the character using it thrusting their palms forward to release a surge of spirit energy, or Ki. The most common input for the Hadoken is moving the control stick a quarter-circle towards your opponent, and pressing a punch button, with the Hadoken's power and speed depending on which punch button was pressed. Takashi Nishiyama, the creator of Street Fighter, credits a weapon from the 1970's anime Space Battle Yamato, the Hadōhō (波動砲, lit. Wave Motion Gun/Surge Cannon), as the inspiration behind the Hadoken.

The Shakunetsu Hadoken made its Street Fighter debut in Super Street Fighter II: The New Challengers as a new move for Ryu's arsenal; it function as a red-colored, flaming Hadoken that could burn the opponent. This red coloration could also be seen on the Hadoken in the original Street Fighter through an easter egg (previously thought to be a glitch), which led to speculation that this "red Hadoken" was stronger than the normal one, leading Capcom to make the "red Hadoken" a separate move with actual property differences (such as knocking fighters down up close) from the normal Hadoken. In Street Fighter III and Street Fighter IV, Shakunetsu Hadoken serves as the EX version of Hadoken.