Tabuu Whip glitch
If a character air dodges or techs into Tabuu's Chain of Light, they will get stuck beneath Tabuu's legs and be unable to free themself until Tabuu KOs them. Being under the effects of a Metal Box can also cause this glitch.
If performed correctly, the character enters a basic, no-animation T-pose, and will "follow" Tabuu, teleporting around the stage with Tabuu until he uses a move that makes the character flinch. This glitch is possibly caused by not flinching. The glitch may work when a character in Adventure Mode has a strong launch resistance sticker attached, a Super Mushroom, or a Metal Box and very little to no damage, but only on the lower difficulties. It may also rarely occur in Boss Battles if a player techs into the attack on Easy difficulty at 0%.
A variation of the glitch can be performed in co-op mode by having one character land the final blow on Tabuu while the other is caught in the Chain of Light (it's possible this can also be done by one player with a slow-acting projectile). Tabuu will be defeated without releasing the character from his grab, resulting in that character being frozen in a tumbling pose in the center of the stage while Tabuu falls away, and disappearing at the same time the boss does if a loose explosive does not knock them out.
The primary result of the glitch (being attached to Tabuu without animating) is due to the character being attached to Tabuu's throwing bone in circumstances that lack matching animations for the thrown character. The cause of the first variation of the glitch is unclear, but the second variation is due to bosses not flinching and therefore being immune to having characters they are grabbing from being released if they are hit. Since there is no record of this occurring with Master Hand or Crazy Hand, it's reasonable to assume that the glitch only occurs because it's not possible to escape the Chain of Light (as opposed to the Hands' grabs).