Do you need both Joy-Cons for Smash?

Do you need both Joy-Cons for Smash? Each player can choose between a single Joy-Con, a pair of Joy-Con controllers, a Pro Controller, or GameCube controller (GameCube controller adapter required). For players using a single Joy-Con, hold the controller horizontally and press the SL and SR buttons on top.

Each player can choose between a single Joy-Con, a pair of Joy-Con controllers, a Pro Controller, or GameCube controller (GameCube controller adapter required). For players using a single Joy-Con, hold the controller horizontally and press the SL and SR buttons on top.