@ROCKINHOPPER It’s because it’s a pure grass type and in gen 3 (when sceptile was introduced) all grass moves were special attacks. Moves did not become individually categorised between physical and special until gen 4 (diamond and pearl) before that it was based on type
@soulsilverart Most likely they are one of a kind variants like the blood moon ursaluna and if they are ever in the main series then I would expect them to be obtained at the end of a side quest.