Realistic Wario & Waluigi
Keeping us all on our toes, the far more obvious choices for realistic-means-nightmares characters would be Wario and Waluigi. But no, instead we get something much closer to how the nefarious pair would look were they to appear in real life.
Oh my goodness, they’d better show up in the forthcoming Mario movie, just so when they inevitably become the stand-out fan-favorites, they get their own spin-off sequel, and North of the Border can work as part of the design team for the project.