Archetypes in Yu-Gi-Oh! can be traced back to a single type of monsters; Archfiends. This is only if you consider it retroactively, however, and therein lies the problem with creating an archetype where none exists.
Don’t get me wrong, archetypes are a fun way to add new deck strategies to the game, even if the current meta has an over reliance on them, but I digress. Officially, Archfiends started with Dark Crisis as we all know – as distinguished by the ‘Archfiend’ in their names. Go figure. But in Japan, there were a few more cards in this pool; cards that had nothing to do with the current archetype, but still fall under its rulings simply because its Japanese name includes the extremely generic term “Demon”. This short-sighted move was done only with the intention of grouping in Summoned Skull, but also had the consequence of adding a bunch of other random cards, like Axe of Despair, Beast of Talwar, Shadow Tamer, A Deal With Dark Ruler, Beast of Gilfer, Lesser Fiend, Wicked Mirror, and… Air Marmot of Nefariousness, which due to a delayed US release actually did get the name Archfiend Marmot of Nefariousness.
So yeah, theories that this was intended as an archetype from the start are shaky at best. Another revisionist archetype is Phantom Beasts, which bears the distinction of starting the precedent of “archetype condition text”, which further muddies the waters when card titles are being changed at the same time with no consistency. Not even Gazelle the King of Mythical Beasts was safe. Anyways, adding the condition that an effect monster belongs to an archetype isn’t the end of the world, but effect text on a normal monster is just about the ugliest thing I can think of. It’s already confusing enough that players have to either have the new cards that override a card’s name, or just know that they have a property that isn’t listed on the card they have.
What would have been a proper way to hand this? Don’t make archetypes where there are none. Could Archfiends exist without the original Summoned Skull? Yes. Could Phantom Beasts Exist without Gazelle the King of Mythical Beasts? I don’t think I even need to answer that.