Autolanding

Autolanding is a technique for Super Smash Bros. Brawl that was discovered by smashers and  on March 14th, 2008. It consists of attacking immediately upon landing, without receiving any landing lag. The technique is performed by holding down while jumping, and when the player is at the same level of the platform, they must let go of down and perform any attack. This technique can only be performed on platforms that are considered to be moving, specifically the stages below. A player can use this technique to their advantage and attack an unsuspecting opponent from below. It can be a good starter for combos, KOing with fast moves, and other attacks.

Stages in which the technique can be performed

 * Yoshi's Island (SSBB)
 * Lylat Cruise
 * Smashville
 * Pirate Ship
 * Halberd
 * Rainbow Cruise
 * Frigate Orpheon
 * Delfino Plaza (when the stage is rising or setting into the different levels)
 * Shadow Moses Island

Explanation
While the exact reason is unknown, the glitch seems to exist due to an interaction of three things:
 * Characters cannot land on soft platforms when the control stick is held downwards.
 * Characters can only land on platforms if they are moving downwards or the platform moves through their movement.
 * Some sort of mechanic involving the action change from jumping/falling and attacking, or possibly the buffer.