1. Nobody but you seems to want Team Rocket.
2. Tingle is in no way more deserving or more interesting than Toon Link.
3. Kiddy Kong ain't invited.
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4. the Duck Hunt Dog ain't coming.
5. Very few want Impa to replace Sheik or both to make it.
6.That fits your roster sample, even if a lot of your choices are questionable.
7. Again, one newcomer probably takes about as much work as 2 to 2 1/2 (Brawl) characters already in smash. It's simply like business. Nintendo already has their data and statistics and stuff. All Sakurai and co is gonna do is modify many of their moves, transfer over the frames and whatnot, give them new updated (graphically) character models, and maybe a few new attacks. That's it really, along with new frames for stuff like items.
With new characters, you have to design them from scratch, come up with alternate outfits, invent movesets, implement those movesets, and competely start from scratch. This is completely a different scenario from the one you are painting, and probably a more accurate one, too, unless Sakurai starts entirely from scratch. Sakurai only stared mostly from scratch with Brawl.