So everyone should know how to initiate a fast fall. If you don't, you do so by pressing down quickly in the air, you should get a sparkle confirmation in Smash 3DS.



Now onto Fast Fall "Canceling."



In Smash 3DS you can now stop your fast fall by initiating either an aerial move or special move in the air. After the aerial or special move is initiated, your fall speed will return to a "slow," fall speed.



This also means that you can immediately after initiating the aerial, perform a 2nd fast fall in the air. For special moves, you must wait until the special move is completed.



What does this mechanic mean for competitive play? Not much, but it does mean you can fast fall farther offstage to edgeguard or gimp without using double jump to cancel your fast fall to avoid SDing. Unlike in Brawl when D-air initiated a fast fall, then you were likely to kill yourself if the move lasted too long. (Same applies to moves like buffered fast fall Ike's nair offstage in brawl).



Just like airdodge canceling, this is less of a technique, and more so a new mechanic to the Smash series. So Fast Fall Canceling seems like a good generic name if you ask me.



So in short, you can cancel your fast fall with an aerial or special move. (Or a double jump like in every other Smash game). After you have canceled your fast fall, you may immediately initiate a 2nd fast fall. There is no limit on the number of fast falls you can do in one full hop, your only limitation is the speed of your aerial and the ground below you.