|Please note that this article refers to glitches which only exist in the Japanese versions of the specified Pokémon game, or refers to glitches from games which were only released in Japan.|
These glitches do not exist in other translations of the game.
The Swift miss glitch is a glitch in Pokémon Red and Green, Pokémon Blue (Japanese) and Pokémon Yellow (Japanese) where the move Swift (called スピードスター "Speed Star") may miss if the target Pokémon doesn't have a Substitute up.
How to perform
First, you need a Pokémon that knows the move Swift. Various Pokémon learn it through level-up, including Pikachu, Sandshrew, Sandslash, Magnemite, Magneton, Voltorb, Electrode Staryu and Mewtwo. A girl in the Route 12 gate 1F gives the player TM12, which teaches Swift.
When using Swift, the move may miss if the player has no Substitute up ; however, it will always hit a Substitute.
The girl's description of the move is :
スピードスター という わざよ
この わざは めいちゅうりつが
まけられない しょうぶの とき
やくに たつ はずよ
a move called Speed Star.
This move's accuracy rate
is very high.
During a battle you can't lose
it should be useful.
(Thanks IceFlame for the translation) However, the video down below showcases a Pikachu's Swift missing against a Pikachu who used Double Team several times.
Swift has a 1/256 chance of missing anyways, and is affected by Accuracy-reducing and Evasion-raising moves.
This glitch was fixed in all English versions, but the fix introduced the Substitute drain move not missing glitch.
(happens near 2:40 for Pokémon Yellow (Japanese), though it's not obvious if you're not fluent in Japanese)
Thanks to IceFlame for the research.
Original GCLf thread