First Party:
1. King K. Rool
Come on, we finally got Ridley, one of the biggest struggles of Smash is over, the Kremling King is the last classic Nintendo icon left. And really... that's it, he's the only definitive Nintendo character I really need. There are a few more I want, and I don't truly think this can be the ultimate Smash with the likes of Takamaru and others down for the count, but on a completely personal level, K. Rool is my most wanted first party, Ridley was my second.
2. Lip
My most wanted character from a series unrepresented in Smash, Panel de Pon is the best puzzle game ever crafted and she deserves to be remembered.
3. Mike Jones
The best first party NES game, but even more obscure than Takamaru. I'd honestly be surprised if StarTropics got any sort of mention in Smash.
4. Dixie Kong
The best member of the DK crew, it definitely wouldn't be ultimate without her.
And that's really it out of the viable choices left that I have any sort of personal connection with. So here are some honorable mentions.
Ashley - Great character design, super popular, would like to see despite my lack of interest in WarioWare.
Isaac - Haven't played Golden Sun, but his fanbase has stuck by him through thick and thin, I want to see him purely for their sake.
Decidueye - Not terribly into Pokemon, didn't even play SuMo, but this is the most interesting one of the bunch.
Insert New Series Here - Really at this point, I just want to see completely fresh new faces join.
I'm out of characters, so extra honorable mentions to the fallen, Waluigi and Krystal.
Third Party:
I can't even give five third parties, anyone that knows me knows who I want.
Banjo-Kazooie
Even after nearly two decades, it still feels wrong to even list them as third parties. Still a pipe dream to end all pipe dreams, but Smash will never be complete in my heart without them, they should have been in since Melee or Brawl, but now they're so far away.
Rayman
The only third party (that wasn't formerly a Nintendo character) that I truly ever wanted after Snake. Sonic was cool, and I loved Pac-Man, but no one can ever take the limbless wonder's place. The only reason he isn't my absolute most wanted is the above mentioned tragedy of a bear and bird.