Slide is a Low attack that sends your character sliding feet-first at the opponent. It is an archetypal move shared by Law, Lee, and Shaheen, who are often referred to as "Slide Characters." It is generally an unreactable low that knocks down on hit, side-swaps, and requires the opponent to use a specific float combo to punish.
Characters with a Slide can often form a game plan around it by mixing it up with their other moves that can be done from While Standing or Full Crouch like hopkicks.
How to do (still a Work In Progress)
The input is FC d/f,d,d/f+3.
Slide is a move that can only be done while you are in Full Crouch, which means you would have to have been crouching (holding D, DB, or DF) for at least 11 frames in total before Slide will come out. You can use the first input of Slide to buffer the full crouch, but you will also see people input d/b,d/f,d,d/f+3 to make sure they were in FC for long enough. If you are having trouble getting Slide to come out check to make sure that you were crouching for long enough, or that you were cleanly inputting d/f,d,d/f+3 and not something like d/f,d/b,d/f+3.
Here's a good video about Fundamentals by LegendKicker,
this portion needs to be fact-checked, please ignore
Theoretically command screen for the fastest possible Slide would read as as:
| Standing | |
| Full crouch | |
| Half crouch | |
| While standing |