|Please note that this glitch only exists in the Japanese versions of the game, or is otherwise a glitch from a Pokémon game which was only released in Japan.
The warp by Nidoran♂ glitch is a select glitch in Pokémon Red, Green, and Pokémon Blue (Japanese), documented by the Japanese website Pokémon Analysis. It allows the player to warp anywhere based on a Nidoran♂'s current HP.
There are a few specific requirements, and this glitch can be used as an alternative to the dokokashira door glitch. A glitchy Pokémon you get from the glitch however, may (but not always) freeze the game when its picture is viewed in the Hall of Fame, meaning warping to the Hall of Fame (HP = 118) is not recommended.
1) At least 13 items
2) A Pokémon (Pokémon 2) with a Special stat of 7 and a second move with PP greater than 4.
3) A Nidoran♂ (Pokémon 3) with a current HP stat equating to the index number of the map you want to warp to. Note that this stat should be lower than 256.
1) Go to the Name Rater's house in Lavender Town. Alternatively, you can go to the Daycare man on Route 5.
2) Highlight the 12th item with select, exit with B,B, talk to the Name Rater and choose the second Pokémon (that has a Special stat of 7 and at least 4 remaining PP on the second move) to swap it with a glitch Pokémon. The exit mats should be blocked.
3) Highlight the 13th item with select, exit with B,B, talk to the Name Rater and choose the third Pokémon (the Nidoran♂) to swap it with a glitch Pokémon. The left of the exit mat should be blocked, but going through the right exit map should take you to a location corresponding to your Nidoran♂'s current HP.