Made "DefaultForm_X" flag apply when changing a Pokémon's species

Data/Scripts/010_Data/002_PBS data/008_Species.rb

@@ -212,11 +212,16 @@ module GameData
       return GameData::GenderRatio.get(@gender_ratio).single_gendered?
     end
 
-    def base_form
+    def default_form
       @flags.each do |flag|
         return $~[1].to_i if flag[/^DefaultForm_(\d+)$/i]
       end
-      return @form
+      return -1
+    end
+
+    def base_form
+      default = default_form
+      return (default >= 0) ? default : @form
     end
 
     def has_flag?(flag)