I generally refer to them as the Big Eight, the eight mainstays of the series (especially the Mario Kart games) who seem to keep popping up.
Mario, Luigi, Peach, Toad, Bowser, Wario, DK, Yoshi.
Let's just say that Nintendo have elected to chop out one of the characters from the Mario games, and they can never return. No adventures, no spinoffs, no Geno-like token cameos in mini-games, nothing. My question to you is... who would you pick?
For mine, I'd get rid of DK. He probably adds the least to the series storywise and tbh I hate his new voice with a fiery passion.