Use level_int_t for levels.

src/Battling/Library/ExperienceLibrary.hpp

@@ -2,6 +2,8 @@
 #define PKMNLIB_EXPERIENCELIBRARY_HPP
 
 #include <CreatureLib/Battling/Library/ExperienceLibrary.hpp>
+#include <CreatureLib/Defines.hpp>
+
 namespace PkmnLib::Battling {
     class ExperienceLibrary : public CreatureLib::Battling::ExperienceLibrary {
     public: