Add a much needed additional tutorial by popular demand

src/tutorial.ts

@@ -7,6 +7,7 @@ export enum Tutorial {
   Access_Menu = "ACCESS_MENU",
   Menu = "MENU",
   Starter_Select = "STARTER_SELECT",
+  Pokerus = "POKERUS",
   Select_Item = "SELECT_ITEM",
   Egg_Gacha = "EGG_GACHA"
 }
@@ -43,6 +44,12 @@ const tutorialHandlers = {
                         $The IVs for a species are also the best of every one you've\ncaught or hatched, so try to get lots of the same species!`, null, () => scene.ui.showText('', null, () => resolve()), null, true);
     });
   },
+  [Tutorial.Pokerus]:  (scene: BattleScene) => {
+    return new Promise<void>(resolve => {
+      scene.ui.showText(`A daily random 3 selectable starters have a purple border.
+                        $If you see a starter you own with one of these,\ntry adding it to your party. Be sure to check its summary!`, null, () => scene.ui.showText('', null, () => resolve()), null, true);
+    });
+  },
   [Tutorial.Select_Item]: (scene: BattleScene) => {
     return new Promise<void>(resolve => {
       scene.ui.setModeWithoutClear(Mode.MESSAGE).then(() => {

src/ui/starter-select-ui-handler.ts

@@ -986,6 +986,8 @@ export default class StarterSelectUiHandler extends MessageUiHandler {
           this.setSpeciesDetails(species, props.shiny, props.formIndex, props.female, props.abilityIndex, defaultNature);
         }
         this.pokemonSprite.clearTint();
+        if (this.pokerusCursors.find((cursor: integer, i: integer) => cursor === this.cursor && this.pokerusGens[i] === this.genCursor))
+          handleTutorial(this.scene, Tutorial.Pokerus);
       } else {
         this.pokemonGrowthRateText.setText('');
         this.pokemonGrowthRateLabelText.setVisible(false);