Regarding Fire Emblem "oversaturation", one must consider the fact that there's really only three original movesets at play, with Lucina and Roy being derivatives of Marth (Even if Roy might be "Luigified"). That said, five slots are still being occupied, even if 1 of those slots is circumstantial due to it being DLC. That's still 4 slots on the disc.
Zelda has five characters counting both Links and Zelda/Sheik separately, with three unique movesets, Ganondorf's moveset being a pretty significant retool of Falcon's moveset, and Toon Link being a moveset-clone but not so much of a stat-clone. All that said, 5 slots on the disc. Barely more than Fire Emblem without DLC, and on-par with Fire Emblem after DLC.
Zelda as a series has enjoyed more games, more sales, and more popularity than Fire Emblem by and large. One could argue, however, that Zelda is already perfectly represented in terms of Zelda characters. It has the core trio, as well as a couple "bonuses" in Sheik and Toon Link.
Fire Emblem has the original lord, a fairly recent lord, and a lord from the most recent entry, as well as two derivatives, one that was added to Melee to advertise an upcoming game, and another that was added because of how easy it was to make them a clone.
As an aside, Mario is Nintendo's biggest franchise, and has a number of reps that reflects that. Some people are complaining about DK being under-repped (A somewhat valid complaint, all things considered), but maybe the reason it's stuck at two reps is because Nintendo considers Wario, Yoshi, and the DK's as part of the greater Mario series despite different series icons? I mean why else would they not add Dixie Kong and/or King K. Rool? Or a WarioWare character like Ashley or Mona?
