The Pokemon @Lance_Dragonite posted is fan made, a made up concept of a fusion involving Lunala and Cresselia, it was fan titled 'Lunalia' which if you type in google images, you get the photo he used.
So the hint is either referencing the word 'Lunalia' or alluding to 'Lunala' which could be Hybrid King's design or maybe the other pokemon Cresselia.
So the hint is either referencing the word 'Lunalia' or alluding to 'Lunala' which could be Hybrid King's design or maybe the other pokemon Cresselia.