Popping into the thread to share my opinions on Quote.
I LOVE Cave Story, and think that Quote would be a perfect pick for Smash. I also have a theory that he's "Brave", even though I personally don't believe in it. I do think that the option's open, though, however slim a chance!
Brave is short (Ness/Lucas Height). Quote stands at about that comparative to The Doctor, who I think is a regular human but I haven't played CS in forever.
Brave is relatively heavy (Mega Man weight-ish). Mega Man and Quote are both robots and roughly the same height, so they'd probably weigh very similarly.
Brave is slow(ish) on the ground. Quote's speed isn't too fantastic on the ground if memory serves, and it may be for balancing.
Brave is fast in the air. So is Quote, and he could be using the Booster 2.0.
Brave seems to play like a zoner (PAC-MAN, Duck Hunt Duo). Quote, with his tremendous arsenal, would also probably play like a zoner.
BRAVE rhymes with CAVE, and is one letter off BRACE (i.e Curly Brace). This one's a stretch, I know.
Why would Sakurai pick Quote? Surely he's irrelevant.
Cave Story is widely credited as the first big indie game. It also has rereleases all over Nintendo, including an exclusive 3DS game (Cave Story 3D). The legacy of indies is immeasurable, and since CS is the codifier for a lot of them, it's the same argument as, say, Dragon Quest.
I have a moveset drawn up for Quote but I don't want to wall-of-text this thread too badly. I think Quote would fit right into Smash's colourful line-up, and I'd love to support him in any way I can!