Unfortunately, no. This was something I heard at some point somewhere, which sucks. It was probably in this thread too and I'm not looking through 451+ pages even if you pay me.
Ah well. It still sounds pretty fishy to me, I don't doubt that they were among the first chosen, but the very first? I suspect characters like Diddy, Wario, Snake, etc. were probably chosen beforehand.
There is however a source flying around that Sakurai could have picked Ike's Radiant Dawn design, so you can find that. It's in an interview somewhere. and I'm 100% sure about that.
Well it is confirmed that Sakurai wanted a new FE character before he even decided on Ike, and Ike was included due to IS's suggestion, but that's about the extent that's been confirmed I believe.
To add to this, if Subspace Emissary is anything to take from, we know Lucario and Lucas weren't late additions to say the least, but that's not really surprising with Lucas.
SSE was made after the initial group of core newcomers (basically all the newcomers other than Wolf, Toon Link, Sonic, and the Forbidden 7) were finalized to be in the game, so really who has the largest/most-important roles in the SSE isn't really indicative of when they were chosen to be included in Brawl (with a few exceptions ofc).
I mean, they can still get people for a DK64 remake, but it'll be a while. Wasn't there interest around?
Unless it's on the 3DS, it's not going to come from Rare. And IIRC Rare closed their portable division a while ago. And I doubt Microsoft would allow them to work on a game as large as DK64, it'd take away from developing the crap they do now.
That's probably overrepping Pokemon. If we had 5 Pokemon characters than we would have a Mario newcomer and a Zelda newcomer also.
That's not overrepping Pokemon, that's how many Pokemon was going to have in Brawl. Those are actually the exact characters it was going to have in Brawl (minus the new versions ofc).
And Mario, Zelda, and Pokemon DON'T NEED AN EQUAL AMOUNT OF REPS. The only game they even had this in was Brawl, so it's not even a coincidental pattern yet, as it's ONLY HAPPENED ONCE.