The control stick is the grey stick on the Nintendo Gamecube and Nintendo 64 controllers, the white stick on the Nunchuk controller, the two white sticks on the Classic Controller, The black/white sticks on the Wii U GamePad and the Joy-Cons sticks.
In the Super Smash Bros. series, the main control stick positions players need to know are up, down, forward and backward. Forward is the direction a character is facing on-screen, and backward is just the opposite. The control stick can also be smashed to achieve various effects such as Dashing and smash attacks. When handling the Wii Remote in NES Style, the Directional Pad serves as the control stick as there's no control stick on the Wii Remote alone.