Instant Transmission

Instant Transmission is, Kaiō-ken Goku and Super Saiyan Goku's up special move in Super Smash Flash 2. Goku performs a flip kick before teleport in the direction inputted by the player. The move has a fairly fast start-up time and intangibility frames during the teleportation.

The kick at the start deals 12%, considerable vertical knockback and slight horizontal knockback depending on which hitbox connects. With its speed and good knockback scaling it can turn into a good KO tool, especially against floats. If Goku is in Kaiō-ken mode it does 14%, and is slightly faster.

Super Saiyan version
Super Saiyan Goku's Instant Transmission is very similar to standard Goku's but has some different properties: it goes a shorter distance, only deals 10% and less knockback, always launches straight up, does not cause helplessness nor lag if landing on the ground and can be done repeatedly in the air. Additionally, by holding the special button Goku will perform a kick upon reappearing and if held longer he will follow up with a strong meteor attack. Both hits deal 10%.

Origin
Instant Transmission is a technique in the Dragon Ball media franchise that first debuted in chapter #336 from the original Dragon Ball manga, titled "A Three Year Gamble". One of Goku's signature moves, this technique allows him to instantly teletransport from one place to another by locating someone else's ki. Goku was taught this technique by the people of Planet Yardrat while he was training there after his battle with Frieza on Planet Namek. To locate someone's ki, he usually puts his index and middle finger on his forehead in order to concentrate. It can be used to travel really long distances (such as going from a galaxy to another), to go from from the living world to the Other World (where the souls of the deceased go after death) and viceversa, and even to travel outside of time (as shown in Dragon Ball Xenoverse).

While this technique is primarily used by Goku as a means of transport, he has also been shown using it for combat, such as when he instantly teleported in front of Cell in order to hit him directly with a Kamehameha.

Trivia

 * In v0.9b, there was a glitch that caused Goku to fly very far after executing Instant Transmission as Kaiō-ken finished, often leading to SDs or giving Goku a very large extension to his normal recovery.