Its also hilarious that the RPG like franchises give Sakurai some denial in regards to how a character is shown.
It makes sense.
Think of it this way: Mario, Link, Donkey Kong, Samus, etc, they are all starring characters in their franchise. They appear in every game that is part of their series in some way. They have major supporting casts that appear in most, if not all of their games as well.
The RPG series are -very- different.
It's similar to like, if you had to choose a single character, or even as many as 3, to represent the entirety of Final Fantasy.
Who do you choose? You have tons of games to choose from and you need to reach a wide audience. You want to pick characters that resonate with players.
Do you pick the most popular? The most current? A mix of the two? Do you insert your own bias? You have to think about various things when considering a character selection when there are TONS to represent a series and to do it justice.
It's not like Zelda where you don't even have to think about it and can just say Link, Zelda & Ganondorf. You don't even have to play the games and you know those are the obvious choices. You can't just throw in obscure Pokemon and FE characters. They have to mean or represent something. It literally can't just be anyone.
Fire Emblem, Pokemon & MOTHER have no "main character" across their entire series. The only obvious choices are the most well-known, prominent or current characters.
Marth's the original, and in 5 games.
Ike's the only other Lord to star in multiple games (aside from Awakening).
Lucina is only in because she was originally a costume.
Robin is the 'current' character, and was in favor of the more obvious Chrom.
Pikachu is the mascot.
Charizard's the most popular starter.
Lucario is super popular & prominent.
Jigglypuff's along for the ride (was prominent/popular, now just 'lol Fairy/original 12')
Greninja was chosen because he was cool, and turned out he was the most popular new starter anyway. Worked out.
Ness is the only MOTHER character that everyone knows. And he's popular.
There's a little method to the madness outside of "these guys said to use these characters". Even if they didn't choose any of them, or that was a fancy myth or something, these characters would've likely been chosen anyway.