Fixes for struggle

Scripts/Moves/Struggle.as

@@ -1,8 +1,24 @@
 namespace Gen7 {
     [Move effect=Struggle]
-    shared class Struggle : PkmnScript {
-        void OnSecondaryEffect(ExecutingMove@ attack, Pokemon@ target, uint8 hit) override{
-            attack.User.Damage(uint(attack.User.MaxHealth / 4), DamageSource::Struggle);
+    class Struggle : PkmnScript {
+        void ChangeEffectiveness(ExecutingMove@, Pokemon@, uint8, float &inout eff) override {
+            eff = 1;
         }
-    }
+
+        void IsInvulnerable(ExecutingMove@, Pokemon@, bool &inout invul) override {
+            invul = false;
+        }
+
+        void ModifyNumberOfHits(MoveTurnChoice@, uint8 &inout hitcount) override {
+            hitcount = 1;
+        }
+
+        void OnSecondaryEffect(ExecutingMove@ attack, Pokemon@, uint8) override {
+            auto damage = uint(attack.User.MaxHealth / 4);
+            if (damage == 0){
+                damage  = 1;
+            }
+            attack.User.Damage(damage, DamageSource::Struggle);
+        }
+    };
 }