...Is there? Both groups you posted have clear winners (Mario, FE) and losers (Zelda, Xenoblade).
This is why I consider the rotating cast argument sort of a meme, I've seen people use it to argue both for and against including both more or less characters for a series based on both whether they have a rotating cast or not have a rotating cast.
To be fair, the main four in the Super Mario series are pretty much guaranteed to be in every game, and aside from Dr. Mario, all of the characters we've gotten beyond them are ones that stuck, even if they do get relegated to spin-off purgatory (but even then it's not like the spin-offs aren't just as popular).
For Fire Emblem it's rare for characters to have more than one game in the series, and with their current choices, it seems that, aside from Chrom, the only eligible picks are the ones that are in your face right now. This can also be seen with Pokémon since while they didn't have a rotating cast until now, each new game brings a butt ton of characters with it, which seems to cause the same effect since Super Smash Bros. Brawl since the series now has its most important characters. The Legend of Zelda series gets the worst of this, as instead of getting new characters, they just get new versions of Link, and only sometimes is it an actually different character.
EDIT: To be honest, the Super Mario series is the only series with a ton of one-off characters that doesn't have major representational issues, and I'm not just talking about quantity here.