Confusion is the Forward B move of Mewtwo in his Super Smash Bros. Melee appearance. Mewtwo psychokinetically whirls the opponent in front of him around and lets the opponent land clumsily on the ground, doing some minor damage in the process. This is widely considered a very impractical move for its lack of a really damaging or disrupting effect and the opponent usually recovers from the tumble animation before mewtwo recovers from his attack animation.
Confusion is able to reflect projectiles, much like the Reflector of Fox and Falco and the Cape of Mario and Dr. Mario. Unlike those moves, however, the Confusion-reflected projectile still is considered the "property" of the original character and thus is unable to harm the projectile's original owner. However, in a three- or four-way melee situation, Confusion reflected attacks will damage other fighters that didn't use the attack. It also cannot reflect Thunder Jolt, unless used at the exact moment that the attack is used.
Alo confusion can be used on the ground to completely stop momentum or in the air to add a small upward force to the rising animation or used to stall (once and then must touch the groud first) while recovering.
Confusion has a second and actually more practical but more obscure use. Confusion can be used to pull an opponent through a platform. Simply jump up through the platform slightly and activate the move and as you pass back through the bottom your foe will clumsily land there as well. On battlefield you can cause an opponent to panic waste their jump and be unable to recover for an instant kill by pulling them through the right or left edge of the stage. This technique works with any thin obstacle. Also less practical in stages that are too thick mewtwo cannot pull them through the course but will instead pull them directly to the edge which often results in mewtwo getting edge hogged while trying to recover from being off the stage.
Origins
Confusion is a weak Psychic-type move learned by many Psychic types early on. It has, like its name suggests, a chance of confusing the opponent.
Gallery
Mewtwo, redirecting one of Link's arrows back at him with Confusion