Glide
Gliding is a technique available to Meta Knight, Charizard and Pit. It allows the character to glide in the direction they are facing, and angle up or down, similar to the Cape item in Super Mario World. Once gliding, the character cannot turn around. There is no unlockable character with this ability.
Peach possesses a similar ability in SSBM and SSBB, though it is not identical. Differences include the fact that it has timed usage, can be moved forward or back, and cannot change elevation. The player can activate Peach's ability by holding onto the jump button after jumping.
To glide do a jump, then a midair one. If you continue holding down the jump button then you will start gliding. Or you can jump then at the peak of your jump, rapidly tilt the control stick/pad to also start gliding. It should be noted that Meta Knight can also start gliding by using his Shuttle Loop.
To control the glide, the user must tilt forward or down to angle downwards and backward or up to angle upwards. The user will go faster if he or she angles downwards/forwards, and slower if he or she angles upwards/backwards. The glide ends if the user attacks out of it or allows himself or herself to lose all momentum by angling upwards (known as stalling).
Since Shuttle Loop always starts a glide, Meta Knight can technically glide twice in one jump.
All three gliding characters have a unique aerial move when they attack out of gliding.
Gliding after using one's final mid-air jump will put one's character into a helpless state.
Gliding allows characters to achieve especially high speeds. In Pit's case, he can glide at the same speed Captain Falcon can run, a maneuver known as the Athens Dash.