Retrained is the term used to describe a monster that has been reprinted with a new effect and slightly different name, but with the same base ATK and DEF, and usually Level and appearance as well. Examples include "Battle Ox" to "Enraged Battle Ox" and "Magician of Black Chaos" to "Dark Magician of Chaos". Special cases are Harpie Lady 1, Harpie Lady 2, and Harpie Lady 3, which all have the same stats as the original Harpie Lady, but are not all representing the same creature. Rather, they are the three sisters from Harpie Lady Sisters.
The term "retrained" comes from "Retrained Elf Swordsman," a translation of the Japanese name for "Obnoxious Celtic Guard", who is a retrained version of "Elf Swordsman" ("Celtic Guardian").
Retrained monsters are not to be confused with upgraded ones, such as Cannon Soldier MK-2. These, like retrained monsters, are clearly based on existing cards. However, unlike retrained versions, these have higher ATK and/or DEF and an effect meant to improve upon the original.
Retrained Cards
- Ansatsu -> Strike Ninja
- Battle Ox -> Enraged Battle Ox
- Black Luster Soldier -> Black Luster Soldier - Envoy of the Beginning
- Celtic Guardian -> Obnoxious Celtic Guard
- Doll of Demise -> Malice Doll of Demise
- Dryad -> Elemental Mistress Doriado
- Prisman -> Elemental Hero Prisma
- Gaia the Fierce Knight -> Swift Gaia the Fierce Knight or Gaia Knight, the Force of Earth
- Harpie Lady -> Harpie Lady 1 / Harpie Lady 2 / Harpie Lady 3
- Magician of Black Chaos -> Dark Magician of Chaos
- St. Joan -> Guardian Angel Joan
- Summoned Skull -> Skull Archfiend of Lightning -> Archfiend Zombie-Skull
- Swordsman of Landstar -> Comrade Swordsman of Landstar
Alternate Cards
- Abyss Flower + Dark Plant
- Amphibious Bugroth + Ground Attacker Bugroth
- Ancient Lizard Warrior + Stone Armadiller
- Ancient Tree of Enlightenment + Trent
- Archfiend Marmot of Nefariousness + Obese Marmot of Nefariousness
- Armored Rat + Prevent Rat
- Armored Starfish + Hitodenchak
- Armored Zombie + Zanki
- Basic Insect + Invader from Another Dimension
- Bat + Dark Shade
- Beaked Snake + Dig Beak
- Beautiful Headhuntress + Warrior of Tradition
- Binding Chain + Mystical Capture Chain
- Book of Life + Book of Taiyou + Book of Moon + Book of Eclipse
- Butterfly Dagger - Elma + Gladiator Beast's Battle Gladius
- Call of the Mummy + Valhalla, Hall of the Fallen + Teleport
- Change Slime + Gruesome Goo
- Crass Clown + Clown Zombie
- Crawling Dragon + Crawling Dragon #2 + Dragon Zombie + B. Dragon Jungle King
- Darkfire Soldier #1 + Darkfire Soldier #2
- Dark Gray + Ancient One of the Deep Forest
- Dark Witch + LaMoon
- Disk Magician + Holograh
- Dissolverock + The Thing That Hides in the Mud
- Dorover + Liquid Beast
- Droll Bird + Great Bill
- Elemental Hero Wildheart + Tenkabito Shien
- Elephant Statue of Blessing + Elephant Statue of Disaster
- Enchanting Mermaid + Amazon of the Seas
- Eternal Rest + Really Eternal Rest
- Fairywitch + Witch's Apprentice
- Fiend's Hand Mirror + Fairy's Hand Mirror
- Fiend Reflection #1 + Fiend Reflection #2
- Firegrass + Living Vase
- Flame Viper + Serpent Marauder
- Flying Kamakiri #1 + Flying Kamakiri #2
- Gate Deeg + Ghoul with an Appetite
- Gatekeeper + Royal Guard
- Great White + Man-Eating Black Shark
- Green Phantom King + Queen of Autumn Leaves
- Gyakutenno Megami + Empress Judge
- Hard Armor + Headless Knight
- Hard-sellin' Goblin + Hard-sellin' Zombie
- Haniwa + Rock Spirit
- Hiro's Shadow Scout + Meotoko
- Hourglass of Courage + Hourglass of Life
- Invader of the Throne + Protector of the Throne
- Jinzo 7 + Jinzo
- Kaiser Sea Horse + Sea Serpent Warrior of Darkness
- Key Mace + Key Mace #2
- King Fog + LaLa Li-Oon + Violent Rain
- Kunai with Chain + Blast with Chain
- Kurama + Whiptail Crow
- Kuriboh + Winged Kuriboh + Kuribon + Wretched Ghost of the Attic
- Larvas + Mon Larvas
- Lava Battleguard + Swamp Battleguard
- Level Limit - Area A + Level Limit - Area B
- Little Chimera + Fusionist
- Luster Dragon + Luster Dragon #2
- M-Warrior #1 + M-Warrior #2
- Man-Eating Plant + Darkworld Thorns
- Mechanical Snail + Spiked Snail
- Metalmorph + Rare Metalmorph
- Mirror Force + Dark Mirror Force + Radiant Mirror Force
- Morphing Jar + Morphing Jar #2 + Ancient Jar
- Mushroom Man + Mushroom Man #2
- Mystery Hand + The Judgement Hand
- Mystical Elf + Dark Elf
- Mystical Sheep #1 + Mystical Sheep #2
- Nekogal #1 + Nekogal #2
- Nobleman of Crossout + Nobleman of Extermination
- Oscillo Hero + Oscillo Hero #2
- Penguin Soldier + Penguin Knight
- Petit Angel + Shining Friendship
- Pot of Greed + Pot of Avarice + Reckless Greed
- Pot the Trick + Dragon Piper
- Princess of Tsurugi + Queen's Double
- Robbin' Goblin + Robbin' Zombie
- Robolady + Roboyarou
- Rock Ogre Grotto #1 + Steel Ogre Grotto #1 + Steel Ogre Grotto #2
- Rock Ogre Grotto #2 + Stone Ogre Grotto
- Root Water + High Tide Gyojin
- Sasuke Samurai + Sasuke Samurai #2 + Sasuke Samurai #3 + Sasuke Samurai #4
- Skilled Dark Magician + Skilled White Magician
- Skull Dice + Graceful Dice
- Skull Knight + Skull Knight #2
- Skull Servant + The Wandering Doomed
- Spirit of the Books + Crow Goblin
- Succubus Knight + Vishwar Randi
- Swords of Revealing Light + Swords of Concealing Light
- The Furious Sea King + Night Lizard
- Thunder Kid + Electric Lizard
- Trap Hole + Acid Trap Hole + Bottomless Trap Hole + Giant Trap Hole + Treacherous Trap Hole + D.D. Trap Hole + Gemini Trap Hole + Adhesion Trap Hole + Scrap-Iron Trap Hole
- Twin Long Rods #1 + Twin Long Rods #2
- Two-Mouth Darkruler + Twin-Headed Thunder Dragon
- Tyhone + Tyhone #2
- Weather Control + Weather Report
- Wing Egg Elf + Winged Egg of New Life
- Winged Dragon, Guardian of the Fortress #1 + Winged Dragon, Guardian of the Fortress #2
- Yashinoki + Snakeyashi
Upgraded Cards
Monster Cards
- Aqua Madoor -> Neo Aqua Madoor
- Airknight Parshath -> Neo-Parshath, the Sky Paladin -> Avenging Knight Parshath
- Amphibious Bugroth -> Amphibious Bugroth MK-3
- Aqua Madoor -> Neo Aqua Madoor
- Beastking of the Swamps -> King of the Swamp
- Big Core -> B.E.S. Big Core MK-2
- Blue-Eyes White Dragon -> Blue-Eyes Shining Dragon
- Cannon Soldier -> Cannon Soldier MK-2
- Dark Assailant -> Shadowslayer
- Feral Imp -> Des Feral Imp
- Fusilier Dragon, the Dual-Mode Beast -> Beast King Barbaros
- Gilford the Lightning -> Beast King Barbaros
- Larvas -> Mon Larvas
- Flying Fish -> Golden Flying Fish
- Gearfried the Iron Knight->Gearfried the Swordmaster->Phoenix Gearfried
- Goblin Attack Force -> Goblin Elite Attack Force
- Hane-Hane -> Hade-Hane
- Injection Fairy Lily -> Counselor Lily
- Man-Eater Bug -> Nobleman-Eater Bug
- Mid Shield Gardna -> Big Shield Gardna
- Monk Fighter -> Master Monk
- Muka Muka -> Enraged Muka Muka
- Cyber Larva -> Proto-Cyber Dragon -> Cyber Dragon -> Cyber Dragon Zwei -> Cyber Twin Dragon -> Cyber End Dragon -> Chimeratech Fortress Dragon ->Chimeratech Overdragon
- Senju of the Thousand Hands -> Manju of the Ten Thousand Hands
- The Statue of Easter Island -> Moai Interceptor Cannons
- The Unhappy Maiden -> The Unhappy Girl
- Codarus -> Levia-Dragon - Daedalus -> Ocean Dragon Lord - Neo-Daedalus
- Mammoth Graveyard -> Great Mammoth of Goldfine
- Magical Exemplar -> Tempest Magician
Spell Cards
- Umi -> A Legendary Ocean
- Mooyan Curry -> Blue Medicine -> Red Medicine -> Goblin's Secret Remedy -> Soul of the Pure -> Dian Keto the Cure Master
- Sparks -> Raimei -> Hinotama -> Final Flame -> Ookazi -> Tremendous Fire
Trap Cards
Downgraded Cards
Monster Cards
- Black Luster Soldier - Envoy of the Beginning -> Sky Scourge Enrise / Ruin, Queen of Oblivion
- Chaos Emperor Dragon - Envoy of the End -> Sky Scourge Norleras / Demise, King of Armageddon
- Ocean Dragon Lord - Neo-Daedalus -> Judgment Dragon -> Black Rose Dragon
- Dark Magician of Chaos -> Endymion, the Master Magician
Spell Cards
- Change of Heart -> Brain Control -> Mind Control
- Creature Swap -> Creature Seizure
- Dark Hole -> Chaos End
- Emergency Provisions -> Poison of the Old Man -> Mystik Wok
- Harpie's Feather Duster -> Heavy Storm -> Giant Trunade
- Harpie's Feather Duster -> Straight Flush
- Monster Reborn -> Premature Burial -> Monster Reincarnation
- Mystical Space Typhoon -> Mystical Wind Typhoon -> Twister -> Tornado
- Pot of Greed -> Chaos Greed -> Accumulated Fortune -> Cup of Ace
- Raigeki -> Lightning Vortex -> Flash of the Forbidden Spell
- Scapegoat -> Stray Lambs
- Snatch Steal -> Enemy Controller -> Soul Exchange
Trap Cards
- Mirror Force -> Radiant Mirror Force -> Dark Mirror Force
- Sakuretsu Armor -> Widespread Ruin
- Waboku -> Hallowed Life Barrier -> Rainbow Life
- Magic Cylinder -> Reflect Bounder -> Dimension Wall
Transformed Cards
- Airknight Parshath -> Neo-Parshath, the Sky Paladin
- Airknight Parshath -> Darknight Parshath
- Airknight Parshath -> Avenging Knight Parshath
- Armed Dragon LV7 -> Dark Armed Dragon
- Dark Magician -> Dark Sage
- Dark Magician -> Dark Eradicator Warlock
- Dark Magician -> Dark Magician Knight
- Dunames Dark Witch -> Dark Valkyria
- Dark Magician Girl -> Magician's Valkyria
- Freed the Brave Wanderer -> Freed the Matchless General -> Dark General Freed
- Gearfried the Iron Knight -> Gearfried the Swordmaster -> Phoenix Gearfried
- Gigobyte -> Gagagigo -> Giga Gagagigo -> Gogiga Gagagigo
- Hand of Nephthys -> Sacred Phoenix of Nephthys -> Dark Nephthys
- Harpie Girl -> Harpie Lady -> Cyber Harpie Lady
- Harpie's Pet Baby Dragon -> Harpie's Pet Dragon
- Helios - The Primordial Sun -> Helios Duo Megistus -> Helios Trice Megistus
- Horus the Black Flame Dragon LV8 -> Dark Horus
- Inpachi -> Blazing Inpachi -> Charcoal Inpachi -> Woodborg Inpachi
- Lady of Faith -> Dryad -> Elemental Mistress Doriado -> Shadowpriestess of Ohm
- Levia-Dragon - Daedalus -> Ocean Dragon Lord - Neo-Daedalus
- Machine King - B.C. 3000->Machine King Prototype -> Machine King -> Perfect Machine King
- Outstanding Dog Marron -> Mad Dog of Darkness -> Skull Dog Marron -> Mecha-Dog Marron
- Petit Moth -> Larvae Moth -> Great Moth -> Perfectly Ultimate Great Moth
- Psychic Kappa -> Kappa Avenger -> Hyosube
- Rainbow Dragon -> Rainbow Dark Dragon
- Red-Eyes B. Chick -> Red-Eyes Wyvern -> Red-Eyes B. Dragon -> Red-Eyes Darkness Dragon -> Red-Eyes Darkness Metal Dragon
- Ryu-Kishin Clown -> Ryu-Kishin -> Ryu-Kishin Powered
- Simorgh, Bird of Divinity -> Simorgh, Bird of Ancestry -> Dark Simorgh
- Skull Flame -> Supersonic Skull Flame
- Tenkabito Shien -> Great Shogun Shien
- The Creator Incarnate -> The Creator -> The Dark Creator
- The Masked Beast -> Masked Beast Des Gardius
- Thousand Needles -> Two Thousand Needles
- Twinbarrel Dragon -> Blowback Dragon -> Barrel Dragon -> Gatling Dragon
- Ushi Oni -> Giant Ushi Oni
- Vampire Lord -> Vampire Genesis
- Voltanis the Adjudicator -> Dark Voltanis
- Warrior Dai Grepher -> Dark Grepher
- Warrior Lady of the Wasteland -> D.D. Warrior Lady
- Warrior of Zera -> Zeradias, Herald of Heaven -> Archlord Zerato -> Darklord Zerato
- Warrior of Zera -> Mazera DeVille
- Warrior of Zera -> Zera the Mant
- Yubel -> Yubel - Terror Incarnate -> Yubel - The Ultimate Nightmare
LV
- Allure Queen LV3 -> Allure Queen LV5 -> Allure Queen LV7
- Armed Dragon LV3 -> Armed Dragon LV5 -> Armed Dragon LV7 -> Armed Dragon LV10
- Dark Lucius LV4 -> Dark Lucius LV6 -> Dark Lucius LV8
- Dark Mimic LV1 -> Dark Mimic LV3
- Horus the Black Flame Dragon LV4 -> Horus the Black Flame Dragon LV6 -> Horus the Black Flame Dragon LV8
- Masked Knight LV3 -> Masked Knight LV5 -> Masked Knight LV7
- Mystic Swordsman LV2 -> Mystic Swordsman LV4 -> Mystic Swordsman LV6
- Silent Magician LV4 -> Silent Magician LV8
- Silent Swordsman LV3 -> Silent Swordsman LV5 -> Silent Swordsman LV7
- Ultimate Insect LV1 -> Ultimate Insect LV3 -> Ultimate Insect LV5 -> Ultimate Insect LV7
- Winged Kuriboh -> Winged Kuriboh LV9
- Winged Kuriboh -> Winged Kuriboh LV10
Metalmorph
- Jirai Gumo -> Launcher Spider
- Musician King -> Heavy Metal King
- Red-Eyes B. Dragon -> Red-Eyes Black Metal Dragon
- Red-Eyes B. Dragon -> Red-Eyes Darkness Dragon -> Red-Eyes Darkness Metal Dragon
- Zoa -> Metalzoa
Toon Monsters
- Blue-Eyes White Dragon -> Blue-Eyes Toon Dragon
- Cannon Soldier -> Toon Cannon Soldier
- Dark Magician Girl -> Toon Dark Magician Girl
- Gemini Elf -> Toon Gemini Elf
- Goblin Attack Force -> Toon Goblin Attack Force
- Masked Sorcerer -> Toon Masked Sorcerer
- Red Archery Girl -> Toon Mermaid
- Ryu-Ran -> Manga Ryu-Ran
- Summoned Skull -> Toon Summoned Skull
Zombie
- Chthonian Emperor Dragon -> Doomkaiser Dragon
- Crass Clown -> Clown Zombie
- Crawling Dragon -> Dragon Zombie
- Dark Ruler Ha Des -> Revived King Ha Des
- Majestic Mech - Ohka -> Malevolent Mech - Goku En
- Paladin of White Dragon -> Paladin of the Cursed Dragon
- Red-Eyes Darkness Dragon -> Red-Eyes Zombie Dragon
- Zanki -> Armored Zombie
- Skull Archfiend of Lightning-> Archfiend Zombie-Skull
Assault Modes
- Arcanite Magician -> Arcanite Magician/Assault Mode
- Colossal Fighter -> Colossal Fighter/Assault Mode
- Doomkaiser Dragon -> Doomkaiser Dragon/Assault Mode
- Hyper Psychic Blaster -> Hyper Psychic Blaster/Assault Mode
- Red Dragon Archfiend -> Red Dragon Archfiend/Assault Mode
- Stardust Dragon -> Stardust Dragon/Assault Mode