diff --git a/src/system/version_migration/v1_0_4/session_migrators.ts b/src/system/version_migration/v1_0_4/session_migrators.ts
deleted file mode 100644
index 766df68d2fe..00000000000
--- a/src/system/version_migration/v1_0_4/session_migrators.ts
+++ /dev/null
@@ -1,61 +0,0 @@
-import { SessionSaveData } from "../../game-data";
-
-/**
- *  Converts old lapsing modifiers (battle items, lures, and Dire Hit) and
- *  other miscellaneous modifiers (vitamins, White Herb) to any new class
- *  names and/or change in reload arguments.
- *  @param data {@linkcode SessionSaveData}
- */
-export function migrateModifiers(data: SessionSaveData) {
-  data.modifiers.forEach((m) => {
-    if (m.className === "PokemonBaseStatModifier") {
-      m.className = "BaseStatModifier";
-    } else if (m.className === "PokemonResetNegativeStatStageModifier") {
-      m.className = "ResetNegativeStatStageModifier";
-    } else if (m.className === "TempBattleStatBoosterModifier") {
-      const maxBattles = 5;
-      // Dire Hit no longer a part of the TempBattleStatBoosterModifierTypeGenerator
-      if (m.typeId !== "DIRE_HIT") {
-        m.className = "TempStatStageBoosterModifier";
-        m.typeId = "TEMP_STAT_STAGE_BOOSTER";
-
-        // Migration from TempBattleStat to Stat
-        const newStat = m.typePregenArgs[0] + 1;
-        m.typePregenArgs[0] = newStat;
-
-        // From [ stat, battlesLeft ] to [ stat, maxBattles, battleCount ]
-        m.args = [ newStat, maxBattles, Math.min(m.args[1], maxBattles) ];
-      } else {
-        m.className = "TempCritBoosterModifier";
-        m.typePregenArgs = [];
-
-        // From [ stat, battlesLeft ] to [ maxBattles, battleCount ]
-        m.args = [ maxBattles, Math.min(m.args[1], maxBattles) ];
-      }
-    } else if (m.className === "DoubleBattleChanceBoosterModifier" && m.args.length === 1) {
-      let maxBattles: number;
-      switch (m.typeId) {
-      case "MAX_LURE":
-        maxBattles = 30;
-        break;
-      case "SUPER_LURE":
-        maxBattles = 15;
-        break;
-      default:
-        maxBattles = 10;
-        break;
-      }
-
-      // From [ battlesLeft ] to [ maxBattles, battleCount ]
-      m.args = [ maxBattles, Math.min(m.args[0], maxBattles) ];
-    }
-  });
-
-  data.enemyModifiers.forEach((m) => {
-    if (m.className === "PokemonBaseStatModifier") {
-      m.className = "BaseStatModifier";
-    } else if (m.className === "PokemonResetNegativeStatStageModifier") {
-      m.className = "ResetNegativeStatStageModifier";
-    }
-  });
-}
diff --git a/src/system/version_migration/v1_0_4/settings_migrators.ts b/src/system/version_migration/v1_0_4/settings_migrators.ts
deleted file mode 100644
index 59955d53352..00000000000
--- a/src/system/version_migration/v1_0_4/settings_migrators.ts
+++ /dev/null
@@ -1,14 +0,0 @@
-import { SettingKeys } from "../../settings/settings";
-
-/**
- * Migrate from "REROLL_TARGET" property to {@linkcode
- * SettingKeys.Shop_Cursor_Target}.
- * @param data the `settings` object
- */
-export function fixRerollTarget(data: Object) {
-  if (data.hasOwnProperty("REROLL_TARGET") && !data.hasOwnProperty(SettingKeys.Shop_Cursor_Target)) {
-    data[SettingKeys.Shop_Cursor_Target] = data["REROLL_TARGET"];
-    delete data["REROLL_TARGET"];
-    localStorage.setItem("settings", JSON.stringify(data));
-  }
-}
diff --git a/src/system/version_migration/v1_0_4/system_migrators.ts b/src/system/version_migration/v1_0_4/system_migrators.ts
deleted file mode 100644
index 8d40c0985b9..00000000000
--- a/src/system/version_migration/v1_0_4/system_migrators.ts
+++ /dev/null
@@ -1,56 +0,0 @@
-import { AbilityAttr, defaultStarterSpecies, DexAttr, SystemSaveData } from "../../game-data";
-import { allSpecies } from "../../../data/pokemon-species";
-
-/**
- * Migrate ability starter data if empty for caught species
- * @param data {@linkcode SystemSaveData}
- */
-export function migrateAbilityData(data: SystemSaveData) {
-  if (data.starterData && data.dexData) {
-    // Migrate ability starter data if empty for caught species
-    Object.keys(data.starterData).forEach(sd => {
-      if (data.dexData[sd]?.caughtAttr && (data.starterData[sd] && !data.starterData[sd].abilityAttr)) {
-        data.starterData[sd].abilityAttr = 1;
-      }
-    });
-  }
-}
-
-/**
- * Populate legendary Pokémon statistics if they are missing
- * @param data {@linkcode SystemSaveData}
- */
-export function fixLegendaryStats(data: SystemSaveData) {
-  if (data.gameStats && (data.gameStats.legendaryPokemonCaught !== undefined && data.gameStats.subLegendaryPokemonCaught === undefined)) {
-    data.gameStats.subLegendaryPokemonSeen = 0;
-    data.gameStats.subLegendaryPokemonCaught = 0;
-    data.gameStats.subLegendaryPokemonHatched = 0;
-    allSpecies.filter(s => s.subLegendary).forEach(s => {
-      const dexEntry = data.dexData[s.speciesId];
-      data.gameStats.subLegendaryPokemonSeen += dexEntry.seenCount;
-      data.gameStats.legendaryPokemonSeen = Math.max(data.gameStats.legendaryPokemonSeen - dexEntry.seenCount, 0);
-      data.gameStats.subLegendaryPokemonCaught += dexEntry.caughtCount;
-      data.gameStats.legendaryPokemonCaught = Math.max(data.gameStats.legendaryPokemonCaught - dexEntry.caughtCount, 0);
-      data.gameStats.subLegendaryPokemonHatched += dexEntry.hatchedCount;
-      data.gameStats.legendaryPokemonHatched = Math.max(data.gameStats.legendaryPokemonHatched - dexEntry.hatchedCount, 0);
-    });
-    data.gameStats.subLegendaryPokemonSeen = Math.max(data.gameStats.subLegendaryPokemonSeen, data.gameStats.subLegendaryPokemonCaught);
-    data.gameStats.legendaryPokemonSeen = Math.max(data.gameStats.legendaryPokemonSeen, data.gameStats.legendaryPokemonCaught);
-    data.gameStats.mythicalPokemonSeen = Math.max(data.gameStats.mythicalPokemonSeen, data.gameStats.mythicalPokemonCaught);
-  }
-}
-
-/**
- * Unlock all starters' first ability and female gender option
- * @param data {@linkcode SystemSaveData}
- */
-export function fixStarterData(data: SystemSaveData) {
-  for (const starterId of defaultStarterSpecies) {
-    if (data.starterData[starterId]?.abilityAttr) {
-      data.starterData[starterId].abilityAttr |= AbilityAttr.ABILITY_1;
-    }
-    if (data.dexData[starterId]?.caughtAttr) {
-      data.dexData[starterId].caughtAttr |= DexAttr.FEMALE;
-    }
-  }
-}
diff --git a/src/system/version_migration/version_converter.ts b/src/system/version_migration/version_converter.ts
index 10aa11f7b25..0fcfa9f9fdc 100644
--- a/src/system/version_migration/version_converter.ts
+++ b/src/system/version_migration/version_converter.ts
@@ -2,9 +2,7 @@ import { SessionSaveData, SystemSaveData } from "../game-data";
 import { version } from "../../../package.json";
 
 // --- v1.0.4 (and below) PATCHES --- //
-import * as v1_0_4SessionData from "./v1_0_4/session_migrators";
-import * as v1_0_4SystemData from "./v1_0_4/system_migrators";
-import * as v1_0_4SettingsData from "./v1_0_4/settings_migrators";
+import * as v1_0_4 from "./versions/v1_0_4";
 
 const LATEST_VERSION = version.split(".").map(value => parseInt(value));
 
@@ -16,9 +14,8 @@ export abstract class VersionConverter {
     }
   }
 
-  callMigrators(data: any, migrationObject: Object) {
-    const migrators = Object.values(migrationObject);
-    for (const migrate of migrators) {
+  callMigrators(data: any, migrationArr: readonly any[]) {
+    for (const migrate of migrationArr) {
       migrate(data);
     }
   }
@@ -40,7 +37,7 @@ export class SessionVersionConverter extends VersionConverter {
       case 0:
         if (curPatch <= 4) {
           console.log("Applying v1.0.4 session data migration!");
-          this.callMigrators(data, v1_0_4SessionData);
+          this.callMigrators(data, v1_0_4.sessionMigrators);
         }
       default:
       }
@@ -64,7 +61,7 @@ export class SystemVersionConverter extends VersionConverter {
       case 0:
         if (curPatch <= 4) {
           console.log("Applying v1.0.4 system data migraton!");
-          this.callMigrators(data, v1_0_4SystemData);
+          this.callMigrators(data, v1_0_4.systemMigrators);
         }
       default:
       }
@@ -89,7 +86,7 @@ export class SettingsVersionConverter extends VersionConverter {
       case 0:
         if (curPatch <= 4) {
           console.log("Applying v1.0.4 settings data migraton!");
-          this.callMigrators(data, v1_0_4SettingsData);
+          this.callMigrators(data, v1_0_4.sessionMigrators);
         }
       default:
       }
diff --git a/src/system/version_migration/versions/v1_0_4.ts b/src/system/version_migration/versions/v1_0_4.ts
new file mode 100644
index 00000000000..4131ee4236d
--- /dev/null
+++ b/src/system/version_migration/versions/v1_0_4.ts
@@ -0,0 +1,137 @@
+import { SettingKeys } from "../../settings/settings";
+import { AbilityAttr, defaultStarterSpecies, DexAttr, SystemSaveData, SessionSaveData  } from "../../game-data";
+import { allSpecies } from "../../../data/pokemon-species";
+
+
+export const systemMigrators = [
+  /**
+   * Migrate ability starter data if empty for caught species
+   * @param data {@linkcode SystemSaveData}
+   */
+  function migrateAbilityData(data: SystemSaveData) {
+    if (data.starterData && data.dexData) {
+      // Migrate ability starter data if empty for caught species
+      Object.keys(data.starterData).forEach(sd => {
+        if (data.dexData[sd]?.caughtAttr && (data.starterData[sd] && !data.starterData[sd].abilityAttr)) {
+          data.starterData[sd].abilityAttr = 1;
+        }
+      });
+    }
+  },
+
+  /**
+   * Populate legendary Pokémon statistics if they are missing
+   * @param data {@linkcode SystemSaveData}
+   */
+  function fixLegendaryStats(data: SystemSaveData) {
+    if (data.gameStats && (data.gameStats.legendaryPokemonCaught !== undefined && data.gameStats.subLegendaryPokemonCaught === undefined)) {
+      data.gameStats.subLegendaryPokemonSeen = 0;
+      data.gameStats.subLegendaryPokemonCaught = 0;
+      data.gameStats.subLegendaryPokemonHatched = 0;
+      allSpecies.filter(s => s.subLegendary).forEach(s => {
+        const dexEntry = data.dexData[s.speciesId];
+        data.gameStats.subLegendaryPokemonSeen += dexEntry.seenCount;
+        data.gameStats.legendaryPokemonSeen = Math.max(data.gameStats.legendaryPokemonSeen - dexEntry.seenCount, 0);
+        data.gameStats.subLegendaryPokemonCaught += dexEntry.caughtCount;
+        data.gameStats.legendaryPokemonCaught = Math.max(data.gameStats.legendaryPokemonCaught - dexEntry.caughtCount, 0);
+        data.gameStats.subLegendaryPokemonHatched += dexEntry.hatchedCount;
+        data.gameStats.legendaryPokemonHatched = Math.max(data.gameStats.legendaryPokemonHatched - dexEntry.hatchedCount, 0);
+      });
+      data.gameStats.subLegendaryPokemonSeen = Math.max(data.gameStats.subLegendaryPokemonSeen, data.gameStats.subLegendaryPokemonCaught);
+      data.gameStats.legendaryPokemonSeen = Math.max(data.gameStats.legendaryPokemonSeen, data.gameStats.legendaryPokemonCaught);
+      data.gameStats.mythicalPokemonSeen = Math.max(data.gameStats.mythicalPokemonSeen, data.gameStats.mythicalPokemonCaught);
+    }
+  },
+
+  /**
+   * Unlock all starters' first ability and female gender option
+   * @param data {@linkcode SystemSaveData}
+   */
+  function fixStarterData(data: SystemSaveData) {
+    for (const starterId of defaultStarterSpecies) {
+      if (data.starterData[starterId]?.abilityAttr) {
+        data.starterData[starterId].abilityAttr |= AbilityAttr.ABILITY_1;
+      }
+      if (data.dexData[starterId]?.caughtAttr) {
+        data.dexData[starterId].caughtAttr |= DexAttr.FEMALE;
+      }
+    }
+  }
+] as const;
+
+export const settingsMigrators = [
+  /**
+   * Migrate from "REROLL_TARGET" property to {@linkcode
+   * SettingKeys.Shop_Cursor_Target}.
+   * @param data the `settings` object
+   */
+  function fixRerollTarget(data: Object) {
+    if (data.hasOwnProperty("REROLL_TARGET") && !data.hasOwnProperty(SettingKeys.Shop_Cursor_Target)) {
+      data[SettingKeys.Shop_Cursor_Target] = data["REROLL_TARGET"];
+      delete data["REROLL_TARGET"];
+      localStorage.setItem("settings", JSON.stringify(data));
+    }
+  }
+] as const;
+
+export const sessionMigrators = [
+  /**
+   *  Converts old lapsing modifiers (battle items, lures, and Dire Hit) and
+   *  other miscellaneous modifiers (vitamins, White Herb) to any new class
+   *  names and/or change in reload arguments.
+   *  @param data {@linkcode SessionSaveData}
+   */
+  function migrateModifiers(data: SessionSaveData) {
+    data.modifiers.forEach((m) => {
+      if (m.className === "PokemonBaseStatModifier") {
+        m.className = "BaseStatModifier";
+      } else if (m.className === "PokemonResetNegativeStatStageModifier") {
+        m.className = "ResetNegativeStatStageModifier";
+      } else if (m.className === "TempBattleStatBoosterModifier") {
+        const maxBattles = 5;
+        // Dire Hit no longer a part of the TempBattleStatBoosterModifierTypeGenerator
+        if (m.typeId !== "DIRE_HIT") {
+          m.className = "TempStatStageBoosterModifier";
+          m.typeId = "TEMP_STAT_STAGE_BOOSTER";
+
+          // Migration from TempBattleStat to Stat
+          const newStat = m.typePregenArgs[0] + 1;
+          m.typePregenArgs[0] = newStat;
+
+          // From [ stat, battlesLeft ] to [ stat, maxBattles, battleCount ]
+          m.args = [ newStat, maxBattles, Math.min(m.args[1], maxBattles) ];
+        } else {
+          m.className = "TempCritBoosterModifier";
+          m.typePregenArgs = [];
+
+          // From [ stat, battlesLeft ] to [ maxBattles, battleCount ]
+          m.args = [ maxBattles, Math.min(m.args[1], maxBattles) ];
+        }
+      } else if (m.className === "DoubleBattleChanceBoosterModifier" && m.args.length === 1) {
+        let maxBattles: number;
+        switch (m.typeId) {
+        case "MAX_LURE":
+          maxBattles = 30;
+          break;
+        case "SUPER_LURE":
+          maxBattles = 15;
+          break;
+        default:
+          maxBattles = 10;
+          break;
+        }
+
+        // From [ battlesLeft ] to [ maxBattles, battleCount ]
+        m.args = [ maxBattles, Math.min(m.args[0], maxBattles) ];
+      }
+    });
+
+    data.enemyModifiers.forEach((m) => {
+      if (m.className === "PokemonBaseStatModifier") {
+        m.className = "BaseStatModifier";
+      } else if (m.className === "PokemonResetNegativeStatStageModifier") {
+        m.className = "ResetNegativeStatStageModifier";
+      }
+    });
+  }
+] as const;