A roll cancel is a movement technique that allows Mario to instantaneously cancel a roll with a cap throw. If performed at the correct angle, Mario can retain his speed from the roll or even redirect it in a different direction.
A roll cancel is performed by pressing X or Y, followed almost immediately by A or B (the buttons can also be pressed simultaneously). This will cause Mario to break out of the roll and throw Cappy in the direction that the joystick is being held.
In two-player mode, the window to perform the second input is smaller, meaning the two buttons should be pressed at the same time.
An "instant roll cancel" refers to a roll cancel that is executed immediately after initiating the roll. To perform an instant roll cancel, one must press X+Y+B, Y+X+B, or any equivalent button combination in rapid succession.
If the roll cancel is performed at an angle that is between roughly 80 and 130 degrees apart from the direction of the roll, Mario's speed from rolling will be conserved and redirected into his running speed. In this case, his running speed will be in the direction of the roll cancel, not the direction of the initial roll. However, Mario's speed can be kept in the direction of the initial roll by immediately following the roll cancel with a jump; this technique is commonly known as a "roll cancel jump". If the jump is performed too late, Mario's speed will be directed in the direction of the roll cancel instead. (This can actually be beneficial rather than detrimental in certain scenarios.)
Motion roll cancels
In addition to standard cap throws, roll cancels can also be performed with upthrows, downthrows (when using Joy-Cons), spinthrows or forward motion throws. Although upthrows and spinthrows do not appear to occur in a specific direction, the joystick must still be moved in the desired angle of the roll cancel.
Motion roll cancels can be performed by replacing the X or Y press in the roll cancel with a motion input. Since motion inputs have a bit of a delay, the motion input will need to be performed roughly half a second before pressing A or B, unlike standard roll cancels.
Roll cancels on ice
Roll cancels have different properties on surfaces with ice physics. On these surfaces, roll canceling in any direction except directly backward will cause Mario's momentum to be redirected in that direction, unlike on standard surfaces where only specific angles exhibit this property. On ice, this momentum transfer happens in a more direct manner, and rather than Mario's path curving around to follow the direction of the roll cancel like normal, it is immediately channeled directly into the new direction. Roll canceling directly backward will cause Mario's momentum to be channeled opposite the direction of the cap throw.
Because throwing Cappy while on these surfaces redirects Mario's momentum instantaneously, rather than with a slight delay as is the case with standard surfaces, attempting to perform a roll cancel jump at an angle on an icy surface will result in Mario's velocity being redirected in the direction that Cappy is thrown instead of continuing forward as it normally would. To perform a roll cancel jump that continues forward on ice, one must perform the roll cancel directly forward or backward.
Roll cancels are extremely common practice in speedrunning, as they allow Mario to quickly gain speed for various maneuvers. Maneuvers that incorporate roll cancels include roll cancel jumps, falling off of platforms and activating objects using Cappy.
Performing an instant roll cancel from the edge of a platform has its uses in trickjumping; namely, for jumps in which the target platform is extremely far away, such as Bruncheon. Although it does not provide any height, this method provides the highest airborne velocity since Mario begins his descent immediately after the roll cancel is performed, meaning there is no opportunity for his speed to be slowed with friction.
Roll cancels can also be used to clip through walls in specific spots in a maneuver known as a roll cancel clip.