The move involves Pit dashing forward, and then uppercutting any opponent he comes across with the Upperdash Arm - similarly to Raptor Boost, although slower and traveling a shorter distance. The move does 11% with mainly vertical knockback, with high base knockback but rather average knockback scaling, making it capable of KOing beginning from 150%. The aerial version is weaker than the grounded version, doing 9% and being unable to KO until 170%. The move uses a proximity detection hitbox to determine when to uppercut, active frames 16-35 on the ground and 19-35 in the air. This is used for opponents and projectiles.
The move has super armor during the uppercut on frames 11-26, allowing Pit to plow through attacks to land a hit. It is also capable of deflecting projectiles while the move is active, though it will cut short Pit's dash, as he will swing his Arm prematurely. Additionally, deflected projectiles are sent upward at a 45 degree angle, and are not considered to be reflected; this renders them harmless to enemies as they are still the property of the opponent, much like how Confusion worked in Melee. It also deals high shield damage to shields. Because of its armor, high shield damage, and ability to deflect projectiles, this move is risky to shield and difficult to counter with attacks alone, although its ending lag makes it easily punished.
If used in the air, the move has an extremely laggy ending animation regardless of whether Pit hits anything (however, more endlag is experienced if Pit misses in the air, enough to make him SD), making the move very punishable if Pit misses. The move itself does not have much landing lag, however. Connecting with it in midair also gives Pit an upward boost that can have its momentum controlled much like a normal jump, and can be performed right afterward once more after the recovery. The ending lag can lead to possible self-destructs if used unwisely, although the move can sweetspot ledges if used as a recovery. Using the move on the ground will cause him to stop at the very edge of whatever platform he's on, similar to Fox Illusion. Despite the massive aerial ending lag, Pit is not put into a helpless state afterwards.
In the Japanese version, Pit may occasionally yell out "Dash Upper!" ("ダッシュアッパー!") upon connecting.
Special Move customization was added in Super Smash Bros. 4. These are the variations:
Arms are one of the weapon classes in Kid Icarus Uprising. Weapons in this class boast power in both melee and ranged combat, but are short-ranged and have a slow attack speed (in addition to considerably slowing Pit's running speed); this is referenced by Pit's move in Smash 4, having good knockback but suffering punishable ending lag. The Upperdash Arm has weak normal attacks but strong melee dash attacks. The back-dash charged shot from this weapon is capable of sending foes airborne.