diff --git a/data/rulesets.ts b/data/rulesets.ts
index 257dafe6fe..1e43f0b63d 100644
--- a/data/rulesets.ts
+++ b/data/rulesets.ts
@@ -1525,6 +1525,34 @@ export const Rulesets: import('../sim/dex-formats').FormatDataTable = {
 		desc: "Forces Pokémon to have a Tera Type matching one of their original types.",
 		// implemented in sametypeclause
 	},
+	samecolorclause: {
+		effectType: 'ValidatorRule',
+		name: 'Same Color Clause',
+		desc: "Forces all Pokémon on a team to share a color",
+		onBegin() {
+			this.add('rule', 'Same Color Clause: Pokémon in a team must be the same color');
+		},
+		onValidateTeam(team) {
+			let color = "";
+			for (const [i, set] of team.entries()) {
+				let species = this.dex.species.get(set.species);
+				if (!species.color) return [`Invalid Pok\u00e9mon ${set.name || set.species}`];
+				if (color && species.color !== color) {
+					return [`All Pok\u00e9mon must share a color.`];
+				}
+				color = species.color;
+				const item = this.dex.items.get(set.item);
+				if (item.megaStone && species.baseSpecies === item.megaEvolves) {
+					species = this.dex.species.get(item.megaStone);
+					color = species.color;
+				}
+				if (item.id === "ultranecroziumz" && species.baseSpecies === "Necrozma") {
+					species = this.dex.species.get("Necrozma-Ultra");
+					color = species.color;
+				}
+			}
+		},
+	},
 	megarayquazaclause: {
 		effectType: 'Rule',
 		name: 'Mega Rayquaza Clause',