Crouch Dash is a movement mechanic that allows access to certain moves while moving forward while also creating evasive properties. Crouch dashes are not universal and multiple types exist.
Due to certain moves (such as hellsweep or EWGF) requiring a CD input, crouch dash can be considered a stance to some extent.
Traditional Mishima-style Crouch Dash
A traditional Mishima-style crouchdash (with a f, n, d, d/f input) can be chained together to rapidly close distance while threatening low, mid, and high options. Multiple wavedashes are often referred to as "wavu wavu."
This type of dash can be canceled into block or ended at any time with a f input, allowing it to be used as a powerful approach tool. Ending this type of crouch dash by default leaves the character in a standing state.
Roll Dash
In addition to traditional crouch dashes, certain characters such as Paul and Bryan have a "roll dash" which is executed with QCF.
This dash cannot be canceled like Mishima-style CD and results in the character in a crouched state.
Additional Types of Crouch Dashes
Some characters, such as Raven, have unique crouch dash options.