Add prependToPhaseWithCondition and use it in SummonPhase to determine speed order

src/battle-scene.ts

@@ -2879,6 +2879,27 @@ export default class BattleScene extends SceneBase {
     return false;
   }
 
+  /**
+   * Prepends a phase to the first occurence of {@linkcode targetPhase} which satisfies {@linkcode condition}
+   *
+   * Pushes the phase to the end of the queue if no occurrence is found
+   * @param newPhase The phase to be added
+   * @param targetPhase The type of phase to search for
+   * @param condition The condition that the target phase must meet
+   */
+  prependToPhaseWithCondition(
+    newPhase: Phase,
+    targetPhase: Constructor<Phase>,
+    condition: (newPhase: Phase, prependPhase: Phase) => boolean,
+  ) {
+    const prependPhase = this.findPhase(phase => phase instanceof targetPhase && condition(newPhase, phase));
+    if (prependPhase) {
+      this.phaseQueue.splice(this.phaseQueue.indexOf(prependPhase), 0, newPhase);
+    } else {
+      this.pushPhase(newPhase);
+    }
+  }
+
   /**
    * Adds a MessagePhase, either to PhaseQueuePrepend or nextCommandPhaseQueue
    * @param message string for MessagePhase

src/phases/summon-phase.ts

@@ -14,6 +14,7 @@ import { GameOverPhase } from "./game-over-phase";
 import { ShinySparklePhase } from "./shiny-sparkle-phase";
 import { MysteryEncounterMode } from "#enums/mystery-encounter-mode";
 import { globalScene } from "#app/global-scene";
+import { Stat } from "#enums/stat";
 
 export class SummonPhase extends PartyMemberPokemonPhase {
   private loaded: boolean;
@@ -283,7 +284,13 @@ export class SummonPhase extends PartyMemberPokemonPhase {
   }
 
   queuePostSummon(): void {
-    globalScene.pushPhase(new PostSummonPhase(this.getPokemon().getBattlerIndex()));
+    // Insert PostSummonPhase in speed order
+    globalScene.prependToPhaseWithCondition(
+      new PostSummonPhase(this.getPokemon().getBattlerIndex()),
+      PostSummonPhase,
+      (newPhase: PostSummonPhase, prependPhase: PostSummonPhase) =>
+        prependPhase.getPokemon().getEffectiveStat(Stat.SPD) < newPhase.getPokemon().getEffectiveStat(Stat.SPD),
+    );
   }
 
   end() {