I would say Vaati, but under the same principles as the DK characters, Vaati has literally had nothing going for him for over a decade. He should be on the chart, but it'd only be out of principle of how he is a viable Zelda character rather than because we could ever realistically expect to see him...
Pig Ganon, on the other hand, seems obscure nonetheless. Don't get me wrong, he makes perfect sense, what with A Link Between Worlds making him a recent face once again, but it reminds me of Sheik versus Impa thing a while back. Since Sheik and Zelda are separated, it would have made perfect sense for Impa to have been the new Sheik, yet rather than taking up the opportunity, Sakurai wanted to keep the veteran as is. In that sense, I don't think I could ever see Ganondorf being turned into Pig Ganon. Pig Ganon being an addition on his own just sounds unrealistic outright when Zelda hardly needs any more characters in the first place. Beast Ganon being Ganondorf's Final Smash, that'd also be strange to see Ganondorf fighting Ganon by turning into Ganon to kill Ganon with the power of Ganon... All this being said for two entirely different characters fighting one another.
I guess my vote goes to No Additions. Sorry Vaati fans.