They could replace Baby Mario with a map and nothing would have changed. How does the Yoshi relay Baby Mario shit even work to begin with? Do they electronically telegraph messages to each Yoshi to stay in a spot for their relay plan?
At this point I’m more and more inclined to believe that since DK’s design originated within Rareware, no DK family driver will have alts. Probably Nintendo bought the rights to use the designs with some additional conditions we are unaware of.
Nintendo owns all of Donkey Kong's franchise and can do whatever with it. Otherwise, there wouldn't exist such drastic design deviations post-Rare buyout such as what Zelen posted, or King K. Rool's pharaoh outfit in Mario baseball.
I don't want to go down the pessimistic route of "they just don't care about the franchise" either since they obviously cared enough to put Funky and Dixie in Mario Kart. Although that argument would come from an understandable place seeing as how they've made zero new DK games in the past 7 years.