diff --git a/src/data/balance/pokemon-evolutions.ts b/src/data/balance/pokemon-evolutions.ts
index 64409c3c989..cf1e4061987 100644
--- a/src/data/balance/pokemon-evolutions.ts
+++ b/src/data/balance/pokemon-evolutions.ts
@@ -9,14 +9,14 @@ import { Nature } from "#enums/nature";
 import { Biome } from "#enums/biome";
 import { Moves } from "#enums/moves";
 import { Species } from "#enums/species";
-import { TimeOfDay } from "#enums/time-of-day";
-import { DamageMoneyRewardModifier, ExtraModifierModifier, MoneyMultiplierModifier, TempExtraModifierModifier } from "#app/modifier/modifier";
 import { SpeciesFormKey } from "#enums/species-form-key";
+import { TimeOfDay } from "#enums/time-of-day";
+import { DamageMoneyRewardModifier, ExtraModifierModifier, MoneyMultiplierModifier, SpeciesStatBoosterModifier, TempExtraModifierModifier } from "#app/modifier/modifier";
+import type { SpeciesStatBoosterModifierType } from "#app/modifier/modifier-type";
 import { speciesStarterCosts } from "./starters";
 import i18next from "i18next";
 import { initI18n } from "#app/plugins/i18n";
 
-
 export enum SpeciesWildEvolutionDelay {
   NONE,
   SHORT,
@@ -1793,8 +1793,9 @@ export const pokemonEvolutions: PokemonEvolutions = {
     new SpeciesEvolution(Species.DUSKNOIR, 1, EvolutionItem.REAPER_CLOTH, null, SpeciesWildEvolutionDelay.VERY_LONG)
   ],
   [Species.CLAMPERL]: [
-    new SpeciesEvolution(Species.HUNTAIL, 1, EvolutionItem.LINKING_CORD, new GenderEvolutionCondition(Gender.MALE /* Deep Sea Tooth */), SpeciesWildEvolutionDelay.VERY_LONG),
-    new SpeciesEvolution(Species.GOREBYSS, 1, EvolutionItem.LINKING_CORD, new GenderEvolutionCondition(Gender.FEMALE /* Deep Sea Scale */), SpeciesWildEvolutionDelay.VERY_LONG)
+    // TODO: Change the SpeciesEvolutionConditions here to use a bespoke HeldItemEvolutionCondition after the modifier rework
+    new SpeciesEvolution(Species.HUNTAIL, 1, EvolutionItem.LINKING_CORD, new SpeciesEvolutionCondition(p => p.getHeldItems().some(m => m instanceof SpeciesStatBoosterModifier && (m.type as SpeciesStatBoosterModifierType).key === "DEEP_SEA_TOOTH")), SpeciesWildEvolutionDelay.VERY_LONG),
+    new SpeciesEvolution(Species.GOREBYSS, 1, EvolutionItem.LINKING_CORD, new SpeciesEvolutionCondition(p => p.getHeldItems().some(m => m instanceof SpeciesStatBoosterModifier && (m.type as SpeciesStatBoosterModifierType).key === "DEEP_SEA_SCALE")), SpeciesWildEvolutionDelay.VERY_LONG)
   ],
   [Species.BOLDORE]: [
     new SpeciesEvolution(Species.GIGALITH, 1, EvolutionItem.LINKING_CORD, null, SpeciesWildEvolutionDelay.VERY_LONG)
diff --git a/src/modifier/modifier-type.ts b/src/modifier/modifier-type.ts
index 4c61123eb2d..912e12f19dc 100644
--- a/src/modifier/modifier-type.ts
+++ b/src/modifier/modifier-type.ts
@@ -873,7 +873,7 @@ export class SpeciesStatBoosterModifierType
   extends PokemonHeldItemModifierType
   implements GeneratedPersistentModifierType
 {
-  private key: SpeciesStatBoosterItem;
+  public key: SpeciesStatBoosterItem;
 
   constructor(key: SpeciesStatBoosterItem) {
     const item = SpeciesStatBoosterModifierTypeGenerator.items[key];
@@ -1440,34 +1440,59 @@ class SpeciesStatBoosterModifierTypeGenerator extends ModifierTypeGenerator {
       stats: [Stat.ATK, Stat.SPATK],
       multiplier: 2,
       species: [Species.PIKACHU],
+      rare: true,
     },
     THICK_CLUB: {
       stats: [Stat.ATK],
       multiplier: 2,
       species: [Species.CUBONE, Species.MAROWAK, Species.ALOLA_MAROWAK],
+      rare: true,
     },
     METAL_POWDER: {
       stats: [Stat.DEF],
       multiplier: 2,
       species: [Species.DITTO],
+      rare: true,
     },
     QUICK_POWDER: {
       stats: [Stat.SPD],
       multiplier: 2,
       species: [Species.DITTO],
+      rare: true,
+    },
+    DEEP_SEA_SCALE: {
+      stats: [Stat.SPDEF],
+      multiplier: 2,
+      species: [Species.CLAMPERL],
+      rare: false,
+    },
+    DEEP_SEA_TOOTH: {
+      stats: [Stat.SPATK],
+      multiplier: 2,
+      species: [Species.CLAMPERL],
+      rare: false,
     },
   };
 
-  constructor() {
+  constructor(rare: boolean) {
     super((party: Pokemon[], pregenArgs?: any[]) => {
       const items = SpeciesStatBoosterModifierTypeGenerator.items;
       if (pregenArgs && pregenArgs.length === 1 && pregenArgs[0] in items) {
         return new SpeciesStatBoosterModifierType(pregenArgs[0] as SpeciesStatBoosterItem);
       }
 
-      const values = Object.values(items);
-      const keys = Object.keys(items);
-      const weights = keys.map(() => 0);
+      // Get a pool of items based on the rarity.
+      const keys: (keyof SpeciesStatBoosterItem)[] = [];
+      const values: (typeof items)[keyof typeof items][] = [];
+      const weights: number[] = [];
+      for (const [key, val] of Object.entries(SpeciesStatBoosterModifierTypeGenerator.items)) {
+        if (val.rare !== rare) {
+          continue;
+        }
+        values.push(val);
+        keys.push(key as keyof SpeciesStatBoosterItem);
+        weights.push(0);
+      }
 
       for (const p of party) {
         const speciesId = p.getSpeciesForm(true).speciesId;
@@ -1846,7 +1871,7 @@ export type GeneratorModifierOverride = {
   count?: number;
 } & (
   | {
-      name: keyof Pick<typeof modifierTypes, "SPECIES_STAT_BOOSTER">;
+      name: keyof Pick<typeof modifierTypes, "SPECIES_STAT_BOOSTER" | "RARE_SPECIES_STAT_BOOSTER">;
       type?: SpeciesStatBoosterItem;
     }
   | {
@@ -1874,7 +1899,7 @@ export type GeneratorModifierOverride = {
       type?: EvolutionItem;
     }
   | {
-      name: keyof Pick<typeof modifierTypes, "FORM_CHANGE_ITEM">;
+      name: keyof Pick<typeof modifierTypes, "FORM_CHANGE_ITEM" | "RARE_FORM_CHANGE_ITEM">;
       type?: FormChangeItem;
     }
   | {
@@ -1977,7 +2002,8 @@ export const modifierTypes = {
   SUPER_LURE: () => new DoubleBattleChanceBoosterModifierType("modifierType:ModifierType.SUPER_LURE", "super_lure", 15),
   MAX_LURE: () => new DoubleBattleChanceBoosterModifierType("modifierType:ModifierType.MAX_LURE", "max_lure", 30),
 
-  SPECIES_STAT_BOOSTER: () => new SpeciesStatBoosterModifierTypeGenerator(),
+  SPECIES_STAT_BOOSTER: () => new SpeciesStatBoosterModifierTypeGenerator(false),
+  RARE_SPECIES_STAT_BOOSTER: () => new SpeciesStatBoosterModifierTypeGenerator(true),
 
   TEMP_STAT_STAGE_BOOSTER: () => new TempStatStageBoosterModifierTypeGenerator(),
 
@@ -2617,6 +2643,7 @@ const modifierPool: ModifierPool = {
     new WeightedModifierType(modifierTypes.DIRE_HIT, 4),
     new WeightedModifierType(modifierTypes.SUPER_LURE, lureWeightFunc(15, 4)),
     new WeightedModifierType(modifierTypes.NUGGET, skipInLastClassicWaveOrDefault(5)),
+    new WeightedModifierType(modifierTypes.SPECIES_STAT_BOOSTER, 4),
     new WeightedModifierType(
       modifierTypes.EVOLUTION_ITEM,
       () => {
@@ -2713,7 +2740,7 @@ const modifierPool: ModifierPool = {
       }
       return 0;
     }),
-    new WeightedModifierType(modifierTypes.SPECIES_STAT_BOOSTER, 12),
+    new WeightedModifierType(modifierTypes.RARE_SPECIES_STAT_BOOSTER, 12),
     new WeightedModifierType(
       modifierTypes.LEEK,
       (party: Pokemon[]) => {
diff --git a/test/items/light_ball.test.ts b/test/items/light_ball.test.ts
index 91195d0b1e5..cdcffe810fa 100644
--- a/test/items/light_ball.test.ts
+++ b/test/items/light_ball.test.ts
@@ -29,7 +29,7 @@ describe("Items - Light Ball", () => {
   });
 
   it("LIGHT_BALL activates in battle correctly", async () => {
-    game.override.startingHeldItems([{ name: "SPECIES_STAT_BOOSTER", type: "LIGHT_BALL" }]);
+    game.override.startingHeldItems([{ name: "RARE_SPECIES_STAT_BOOSTER", type: "LIGHT_BALL" }]);
     const consoleSpy = vi.spyOn(console, "log");
     await game.classicMode.startBattle([Species.PIKACHU]);
 
@@ -100,7 +100,7 @@ describe("Items - Light Ball", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["LIGHT_BALL"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["LIGHT_BALL"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.ATK, atkValue);
@@ -139,7 +139,7 @@ describe("Items - Light Ball", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["LIGHT_BALL"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["LIGHT_BALL"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.ATK, atkValue);
@@ -178,7 +178,7 @@ describe("Items - Light Ball", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["LIGHT_BALL"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["LIGHT_BALL"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.ATK, atkValue);
@@ -207,7 +207,7 @@ describe("Items - Light Ball", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["LIGHT_BALL"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["LIGHT_BALL"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.ATK, atkValue);
diff --git a/test/items/metal_powder.test.ts b/test/items/metal_powder.test.ts
index 6be7655ec70..e924d75fce9 100644
--- a/test/items/metal_powder.test.ts
+++ b/test/items/metal_powder.test.ts
@@ -29,7 +29,7 @@ describe("Items - Metal Powder", () => {
   });
 
   it("METAL_POWDER activates in battle correctly", async () => {
-    game.override.startingHeldItems([{ name: "SPECIES_STAT_BOOSTER", type: "METAL_POWDER" }]);
+    game.override.startingHeldItems([{ name: "RARE_SPECIES_STAT_BOOSTER", type: "METAL_POWDER" }]);
     const consoleSpy = vi.spyOn(console, "log");
     await game.classicMode.startBattle([Species.DITTO]);
 
@@ -96,7 +96,7 @@ describe("Items - Metal Powder", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["METAL_POWDER"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["METAL_POWDER"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.DEF, defValue);
@@ -129,7 +129,7 @@ describe("Items - Metal Powder", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["METAL_POWDER"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["METAL_POWDER"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.DEF, defValue);
@@ -162,7 +162,7 @@ describe("Items - Metal Powder", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["METAL_POWDER"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["METAL_POWDER"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.DEF, defValue);
@@ -185,7 +185,7 @@ describe("Items - Metal Powder", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["METAL_POWDER"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["METAL_POWDER"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.DEF, defValue);
diff --git a/test/items/quick_powder.test.ts b/test/items/quick_powder.test.ts
index d77f981f04d..fb08d6bc71e 100644
--- a/test/items/quick_powder.test.ts
+++ b/test/items/quick_powder.test.ts
@@ -29,7 +29,7 @@ describe("Items - Quick Powder", () => {
   });
 
   it("QUICK_POWDER activates in battle correctly", async () => {
-    game.override.startingHeldItems([{ name: "SPECIES_STAT_BOOSTER", type: "QUICK_POWDER" }]);
+    game.override.startingHeldItems([{ name: "RARE_SPECIES_STAT_BOOSTER", type: "QUICK_POWDER" }]);
     const consoleSpy = vi.spyOn(console, "log");
     await game.classicMode.startBattle([Species.DITTO]);
 
@@ -96,7 +96,7 @@ describe("Items - Quick Powder", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["QUICK_POWDER"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["QUICK_POWDER"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.SPD, spdValue);
@@ -129,7 +129,7 @@ describe("Items - Quick Powder", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["QUICK_POWDER"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["QUICK_POWDER"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.SPD, spdValue);
@@ -162,7 +162,7 @@ describe("Items - Quick Powder", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["QUICK_POWDER"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["QUICK_POWDER"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.SPD, spdValue);
@@ -185,7 +185,7 @@ describe("Items - Quick Powder", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["QUICK_POWDER"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["QUICK_POWDER"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.SPD, spdValue);
diff --git a/test/items/thick_club.test.ts b/test/items/thick_club.test.ts
index 2a63a60a0e6..350735a363c 100644
--- a/test/items/thick_club.test.ts
+++ b/test/items/thick_club.test.ts
@@ -29,7 +29,7 @@ describe("Items - Thick Club", () => {
   });
 
   it("THICK_CLUB activates in battle correctly", async () => {
-    game.override.startingHeldItems([{ name: "SPECIES_STAT_BOOSTER", type: "THICK_CLUB" }]);
+    game.override.startingHeldItems([{ name: "RARE_SPECIES_STAT_BOOSTER", type: "THICK_CLUB" }]);
     const consoleSpy = vi.spyOn(console, "log");
     await game.classicMode.startBattle([Species.CUBONE]);
 
@@ -96,7 +96,7 @@ describe("Items - Thick Club", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.ATK, atkValue);
@@ -119,7 +119,7 @@ describe("Items - Thick Club", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.ATK, atkValue);
@@ -142,7 +142,7 @@ describe("Items - Thick Club", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.ATK, atkValue);
@@ -179,7 +179,7 @@ describe("Items - Thick Club", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.ATK, atkValue);
@@ -216,7 +216,7 @@ describe("Items - Thick Club", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.ATK, atkValue);
@@ -239,7 +239,7 @@ describe("Items - Thick Club", () => {
 
     // Giving Eviolite to party member and testing if it applies
     await game.scene.addModifier(
-      modifierTypes.SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
+      modifierTypes.RARE_SPECIES_STAT_BOOSTER().generateType([], ["THICK_CLUB"])!.newModifier(partyMember),
       true,
     );
     game.scene.applyModifiers(SpeciesStatBoosterModifier, true, partyMember, Stat.ATK, atkValue);