Rhydon glitch

The Rhydon glitch affects glitch Pokémon with an invalid Pokédex number in Generation I when the Pokédex entry is shown upon catching it. All Pokédex numbers from 001 to 151 contain official Pokémon, and thus are valid.

Mechanics

After the Pokédex entry is displayed upon catching a Pokémon with an invalid Pokédex number, an affected Pokémon will become Rhydon, as a subroutine used when giving the player a Pokémon converts all invalid Pokémon to Rhydon. The Pokémon's moves will be replaced by Rhydon's moves at the level it was caught at. If this Pokémon is sent to Bill's PC, it will become an unstable hybrid Pokémon, with the original glitch Pokémon as the recipient and Rhydon as the donor. Due to all hybrid glitch Pokémon having Pokédex numbers equivalent to official Pokémon, they are not affected by this glitch.

Returning the glitch Pokémon to its original self

To return the unstable Rhydon-glitch Pokémon hybrid back to just the original glitch Pokémon, it must be stabilized. To stabilize an unstable hybrid Pokémon, a Pokémon can be evolved (in the way the glitch Pokémon would), traded to Pokémon Stadium 2, or deposited and withdrawn from Pokémon Day Care. However, the glitch Pokémon will still have the nickname "RHYDON" after being stabilized. This allows these glitch Pokémon to learn every move Rhydon can. Once stabilized, the Pokémon can be traded to the Generation II games.

Methods of avoiding the Rhydon glitch

Obtaining a glitch Pokémon with a Pokédex number less than 152 which is not 000.
Obtaining a glitch Pokémon which doesn't show its Pokédex entry upon capture.
Activating the flag which is the same as the obtained flag for the glitch Pokémon as a method of avoiding the Pokédex entry. For example, Pokédex entries belonging to glitch Pokémon in the No. 000 family (such as MissingNo.) will only appear upon capture if the player has not encountered Cubone.
Obtaining a glitch Pokémon twice, as on the second time Pokédex entry flag will already be obtained and the conversion to Rhydon will no longer take place.
Obtaining the glitch Pokémon by evolution.
Trading the glitch Pokémon from another version to obtain the equivalent glitch Pokémon.

Glitches in the Pokémon games
Multiple generations	Transform glitches • Glitch Trainers • Cloning glitches • Error messages • Arbitrary code execution

Generation I	Glitches • Battle glitches • Overworld glitches -- • 0 ERROR • Broken hidden items • Cable Club escape glitch • Dual-type damage misinformation Experience underflow glitch • Fight Safari Zone Pokémon trick • Glitch City • Item duplication glitch • Item underflow Mew glitch • Old man glitch • Pewter Gym skip glitch • Pokémon merge glitch • Rhydon glitch • Rival twins glitch Select glitches (dokokashira door glitch, second type glitch) • Super Glitch Time Capsule exploit • Walking through walls • ZZAZZ glitch

Generation II	Glitches • Battle glitches Bug-Catching Contest glitch • Celebi Egg glitch • Coin Case glitches • Experience underflow glitch Glitch dimension • Glitch Egg • Teru-sama • Time Capsule exploit • Trainer House glitches • GS Ball mail glitch

Generation III	Glitches • Battle glitches • Overworld glitches Berry glitch • Dive glitch • Pomeg glitch • Glitzer Popping

Generation IV	Glitches • Battle glitches • Overworld glitches Acid rain • GTS glitches • Pomeg glitch • Rage glitch Surf glitch • Tweaking • Pal Park Retire glitch

Generation V	Glitches • Battle glitches • Overworld glitches Charge Beam additional effect chance glitch • Charge move replacement glitch • Choice item lock glitch Frozen Zoroark glitch • Sky Drop glitch

Generation VI	Glitches • Battle glitches • Overworld glitches Charge Beam additional effect chance glitch • Charge move replacement glitch • Choice item lock glitch Lumiose City save glitch • Symbiosis Eject Button glitch • Toxic sure-hit glitch

Generation VII	Glitches • Battle glitches • Overworld glitches Charge Beam additional effect chance glitch • Charge move replacement glitch • Choice item lock glitch Toxic sure-hit glitch • Rollout storage glitch

Generation VIII	Glitches Charge Beam additional effect chance glitch • Charge move replacement glitch • Choice item lock glitch Toxic sure-hit glitch • Rollout storage glitch • Party item offset glitch

Generation IX	Glitches

Glitch effects	Game freeze • Glitch battle • Glitch song Gen I only: Glitch screen • TMTRAINER effect • Inverted sprite Gen II only: Glitch dimension

Lists	Glitches (GO • Mystery Dungeon • TCG GB • Spin-off) Glitch Pokémon (Gen I • Gen II • Gen III • Gen IV • Gen V • Gen VI • Gen VII • Gen VIII) Glitch moves (Gen I) • Glitch types (Gen I • Gen II)

This article is part of Project GlitchDex, a Bulbapedia project that aims to write comprehensive articles on glitches in the Pokémon games.