Tumbling

Tumbling (also called DamageFall) is an airborne state that a character enters after being hit or pushed in a certain way (an example of this would be ledge slipping). A character who is tumbling can be identified by the rotation animation they're in or in a lying down animation while in the air. Characters will tumble after being hit in the air by an attack with high knockback or being pushed off the ledge.

Possible actions while tumbling
Tumbling is not the same as being in a helpless state and when the hitstun ends, characters can carry out most normal airborne actions while tumbling:
 * They can move left and right through the air as per normal.
 * Characters are not able to air dodge while tumbling just like in Super Smash Bros. Melee which forces them to either to use their midair jump or attack. Characters are able to zair (tether recovery).
 * Characters can tech if they're about to hit a platform.

Reeling
Reeling (or DamageFlyRoll) is a state that is similar to tumbling, but characters instead enter a helix motion. Characters will enter this state after being hit by an attack that deals high knockback or a few attacks at high percentages. During this state, characters cannot do anything, but D.I. or tech if they come into contact with a platform, wall or ceiling. Once the knockback diminishes and the character slows down, reeling ends and tumbling begins. Reeling happens around 52-55% damage.

Trivia

 * Characters go into a tumbling state when they're Star KO'ed.