The control stick, also known as the analogue stick or joystick, is the gray stick on the Nintendo GameCube and Nintendo 64 controllers, the white stick on the Nunchuk, the two white sticks on the Classic Controller, the white or black sticks of the Wii U GamePad and Wii U Pro Controller, and the black sticks on the Nintendo Switch's Joy-Con and Pro Controllers.
The Nintendo 3DS has a Circle Pad, a sliding gray pad that serves as a handheld counterpart to the control stick. A peripheral for the 3DS, the Circle Pad Pro, adds an extra circle pad on the right side. However, Super Smash Bros. for Nintendo 3DS is not compatible with the Circle Pad Pro, despite being compatible with the C-Stick on the New Nintendo 3DS. This is due to hardware limitations in the standard 3DS that are not present in the New 3DS, due to its better hardware.
In the Super Smash Bros. series, the control stick has four primary directions that can be input. During gameplay, tilting the control stick sideways will make a character walk in that direction. Tilting the control stick downward will make a character crouch if on the ground or fast fall if the character is airborne. Tilting the control stick upwards will cause a character to jump, but only if the Tap Jump control function is enabled for the player. Inputting a regular attack while the control stick is tilted will result in a tilt attack. The control stick can also be directed in diagonal directions, which will allow for more precise movement in the air as well as allowing some attacks to be angled. Pushing this control stick hard will result in dashing and also increases the power of moves such as Samus's Missile. If outside of gameplay, the control stick can be used to navigate the menu.
On the Classic Controller, Wii U GamePad, Wii U Pro Controller, Joy-Con, and the Switch Pro Controller, the left control stick is used for movement, while the right control stick (officially called "right stick"), analogous to the GameCube C-Stick, is used for smash attacks. When the control stick is pushed in any direction, the pertaining smash attack will be executed immediately.
When using a single Joy-Con, the sole control stick serves as what would be the left control stick on other controllers. Additionally, clicking down the control stick in combination with one of the four face buttons will activate a taunt.
Ultimate adds an option in the Controls setting to alter the left stick sensitivity. Doing so alters the window to register a directional input as a "stick flick", and therefore to perform smash attacks and "smashed" special moves like the aforementioned Missile; a lower sensitivity means a stricter window while higher sensitivity means a larger window.