I don't think i can really be argued that "reps" for series do, in fact, exist.
It is not micromanaged to the point that each series is given a number specifically, but there is definitely a ratio of what can be expected to be seen.
Mario, Pokemon and Zelda will remain on top; this reflects Nintendo and is a proportion that we can reliably predict, it also feels right. I doubt we would have two Links or even Sheik if having a large number of Zelda characters were truly important, because the series would be fine with just the main Three. Pokemon and Mario are weird examples, given the vast characters and mediums of one, and the sister-series of the other, but they certainly still deserve to be on top in representatives.
In fact, I'd say, to bring the conversation back to WFT, she was included because the series, being so booming as the 4th largest selling game for Nintendo, deserved a rep enough to inspire Nintendo.
I think the fact that we have so many avatar characters proves that 'reps' exist. Villager, WFT, the Miis, and Robin, are l representative of something more in their series; as was Pokemon trainer. In the case of Villager in particular, he is a rep of his series.
I don't hold steadfast to thoughts thinking a series cannot be lowered in roster representation, though. Lucas was unnecessary in the first place, and even being one of my top 5 most played Brawl characters, he is superfluous and expendable when it comes to Nintendo, and quite honestly Mother is lucky to get even one character, at least, as early in the series as it did.