I'm not talking about characters that best represent the many things that make up their franchise. I'm talking about characters themselves that define those franchises. Franchise mascots, you could say. The characters that the franchise revolves around most. It's more difficult to choose stand out mascots for franchises like Fire Emblem and Pokémon, but I think Marth, Ike, and Chrom are obvious examples of such. I see no reason to cut either Marth or Ike (I don't see the point in cutting one character for another), and with the success of Awakening, it'd be silly for them to not include a new Fire Emblem character, and Chrom is undoubtedly the "mascot" of Fire Emblem Awakening.I disagree with that. Fire Emblem is a game about swords, lances, axes, tomes, bows, etc. and to this point only ONE of those has been featured. It'd be like if every playable Pokemon in Smash was a normal type.
They may not be representing the many types of classes and weaponry in Fire Emblem, but that doesn't really matter when it comes to character inclusion in Smash Bros. What matters is that they're mascots for their franchise. They could have added more unique characters to the roster from the Star Fox and MOTHER/EarthBound franchises, for example, but they went with the most logical choices—the most iconic characters from those franchises; the mascots.