Crouching

Crouching, also known as ducking, is a grounded form of movement in the  series and Fraymakers. Crouching is performed by holding down while standing, which lowers the character's hurtbox and allows them to avoid certain high-profile attacks and projectiles.

In the original Super Smash Flash, crouching primarily allows fighters to utilize their down attack. Players are also able to short hop by jumping while crouching. Due to the game's flawed physics, a bug exists that causes characters to be able to crouch midair by falling from or dropping through a platform while crouching. When this happens, characters are unable to move or attack and need to jump or land on the ground in order to cancel it.

In Super Smash Flash 2 and Fraymakers, crouching behaves closer to how it does in the  series and allows characters to use their down tilt. Characters can also dash cancel by crouching, as well as cancel crouches into dashes, allowing some characters to utilize advanced techniques. Additionally, certain characters are able to crawl while crouching.

Trivia

 * In Super Smash Flash 2, Pichu can heal itself by crouching at a rate of about 1% damage per second. This is disabled in the All-Star Rest Area, however.