>>47040210Original it was pretty simple in gameplay terms:
>only one available in the game>doesn't evolve>can't breed>usually a static encounter, occasionally roaming aroundAlthough now it's a bit harder to say definitively because now you have legendaries you can evolve (Urshifu, Cosmog), legendaries you can get multiple of (also Cosmog), and legendaries that are just straight up handed to you for free (Latios/Latias in ORAS)
As for lore terms it does seem to be pokemon that are ultra rare/one of a kind, are embedded in ancient mythology, or posess great power, but even then there are some that buck that trend like Zarude being a mythical that lives in packs.
