Port weather, copying moves, held items and obedience (#28)

Complete the weather, Substitute, Transform, called-move and forced-switch effects. Add held-item behavior, Exp. Share awards and badge-based traded Pokemon obedience, and persist trainer berry consumption.

Validated with 576 passing unit tests and 149 browser tests, native/reference builds, reference/vendor/release checks and 320 Metal Powder emulator comparisons per browser. Smart AI and special balls/battle types remain on #28.

tests/reference-move-effects.spec.ts

@@ -51,6 +51,7 @@ type Case = {
   beatUpHit: number;
   playerIsSwitching: number;
   enemyIsSwitching: number;
+  weather?: number;
   /** A battle script and the index of the command after the one run. */
   script: number[];
   scriptIndex: number;
@@ -142,6 +143,7 @@ async function compare(page: Page, routines: string[], cases: Case[]) {
     enemyGoesFirst: at("wEnemyGoesFirst"),
     animParam: at("wBattleAnimParam"),
     battleMode: at("wBattleMode"),
+    weather: at("wBattleWeather"),
     partyCount: at("wPartyCount"),
     otPartyCount: at("wOTPartyCount"),
     beatUpHit: at("wBeatUpHitAtLeastOnce"),
@@ -257,6 +259,7 @@ async function compare(page: Page, routines: string[], cases: Case[]) {
           beatUpHit: input.beatUpHit,
           playerIsSwitching: input.playerIsSwitching,
           enemyIsSwitching: input.enemyIsSwitching,
+          weather: input.weather ?? 0,
           script: [...input.script],
           scriptIndex: input.scriptIndex,
         });
@@ -269,6 +272,7 @@ async function compare(page: Page, routines: string[], cases: Case[]) {
         write(addresses.enemyGoesFirst, input.enemyGoesFirst);
         write(addresses.animParam, input.animParam);
         write(addresses.battleMode, input.battleMode);
+        write(addresses.weather, input.weather ?? 0);
         write(addresses.partyCount, input.partyCount);
         write(addresses.otPartyCount, input.otPartyCount);
         write(addresses.beatUpHit, input.beatUpHit);
@@ -621,3 +625,24 @@ test("CheckHit matches Fly, Dig and Lock-On", async ({ page }) => {
   }
   await compare(page, ["BattleCommand_CheckHit"], cases);
 });
+
+test("Stab matches weather, STAB and type effectiveness", async ({ page }) => {
+  const { make, next } = generator(0x57ab);
+  // Normal, Fighting, Flying, Ground, Ghost, Fire, Water, Grass, Electric, Psychic, Dark.
+  const types = [0, 1, 2, 4, 8, 20, 21, 22, 23, 24, 27];
+  const cases: Case[] = [];
+  for (let i = 0; i < 1000; i++) {
+    const input = make({
+      curDamage: [0, 1, 2, 3, 40, 997, 0x7fff, 0xaaaa, 0xffff][next(9)],
+      typeModifier: next(4) ? C.EFFECTIVE : 0,
+    });
+    const user = input.sides[input.turn],
+      target = input.sides[input.turn ^ 1];
+    user.move = { ...user.move, type: types[next(types.length)], effect: next(4) ? 0 : C.EFFECT_SOLARBEAM };
+    user.types = [types[next(types.length)], types[next(types.length)]];
+    target.types = [types[next(types.length)], types[next(types.length)]];
+    if (next(4) === 0) target.sub[0] = 1 << C.SUBSTATUS_IDENTIFIED;
+    cases.push({ ...input, weather: next(4) } as Case);
+  }
+  await compare(page, ["BattleCommand_Stab"], cases);
+});