Metacape glitch
From SmashWiki, the Super Smash Bros. wiki
The Metacape glitch was discovered by the Smasher MetaSnake and is an invincibility/transportation glitch using Meta Knight's Down Special Move. It allows Meta Knight to teleport long distances quickly while invincible. However it can only be performed while utilizing the Floor glitch.
[edit] Performing The Glitch
First, you must create a stage simply with an odd number of small blocks in a horizontal row with an equal number of fall-through platforms directly underneath them, making them hug the bottom. Then, perform the Floor Glitch while in the floor, and face left while standing in the far-right of the blocks. Perform the Dimensional Cape and make sure you tap the control-stick hard. Immediately after the activation (without letting go of the move's controls), rotate the control-stick slightly in the direction you want to go, and hold it until you want to stop. You will self-destruct if you never let go. While moving you are completely invincible and immune to knockback, even to Final Smashes. You can do this glitch from anywhere inside the said floor. It can be performed on almost any custom stage that can utilize the Floor Glitch, but is easier using the stage described above.
[edit] Uses
The Metacape Glitch was discovered recently and so not much is known about its possible uses, however it is a very versatile glitch and so a small list can be made.
First, it can be used along with Meta Knight's up tilt to move anywhere on the stage and attack through the blocks without the risk of your opponent evading or you accumulating damage.
Second, it can be used as a very useful recovery. If you happen to be caught under the described stage, it can be very difficult to get to the ledge and often results in a SD. Instead, try using Drill Rush into the bottom of the stage for a quick and easy recovery free of edge guarding.
More recently, it was discovered that if you press up on the control-stick while teleporting (through the use of the glitch) you will teleport directly upward from the position you were just in onto the top of the block above you and finish with a slash if B is held from the start. This is extremely useful for sneak attacks, and is viable for the best approach in the game.
