Example of creating a local version of OnPossess for Unreal Engine 4

file.cpp

// in game instance header file
virtual void Init() override;

UFUNCTION()
void DispatchPawnControllerChange(APawn* InPawn, AController* InController);

// in game instance cpp file
void UVGameInstanceBase::Init()
{
	Super::Init();

	TScriptDelegate<FWeakObjectPtr> OnPawnControllerChangeDelegate;
	OnPawnControllerChangeDelegate.BindUFunction(this, "DispatchPawnControllerChange");
	OnPawnControllerChangedDelegates.Add(OnPawnControllerChangeDelegate);
}

void UVGameInstanceBase::DispatchPawnControllerChange(APawn* InPawn, AController* InController)
{
	if (!InController)
	{
		UE_LOG(LogTemp, Display, TEXT("Pawn %s was un-possessed"), *InPawn->GetName());
		return;
	}

	if (!InController->IsPlayerController())
	{
		UE_LOG(LogTemp, Display, TEXT("Pawn %s was possessed by non-player controller %s"), *InPawn->GetName(), *InController->GetName());
		return;
	}

	MyPlayerController* PlayerController = Cast<MyPlayerController>(InController);
	if (!PlayerController)
	{
		UE_LOG(LogTemp, Display, TEXT("Pawn %s was possessed by player controller, but not MyPlayerController"), *InPawn->GetName());
		return;
	}

	PlayerController->OnPossessLocal(InPawn); // OnPossessLocal would be a function declared in your custom PlayerController class
	UE_LOG(LogTemp, Display, TEXT("Pawn %s was possessed by MyPlayerController"), *InPawn->GetName());
}