In all honest Shadow Dragon is not a bad place to start, it IS a remake of a NES game so it will feel the 'oldest' out of all of them.
The only thing it has over the other games in the series is class changing and there being save points throughout the map, which aren't that important to the rest of the series.
It's a good place to start because it'll make the other ones seem much better and it has Marth in it.
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