When deciding what characters would appear in the game, Nintendo EPD took inspiration from the original Donkey Kong arcade game, which established that Donkey Kong lived alongside humans. While the team debated how much human-related content and Donkey Kong Country-inspired elements would be included, producer Kenta Motokura mandated that the character Cranky Kong should appear because he was a fan of the character.

It was decided early on that another character would accompany Donkey Kong throughout the game, though no specific character had been included in the software design description. One developer suggested Pauline, with this idea being revisited following the implementation of Donkey Kong's "Zebra Bananza" form. The composer had written music for the transformation sequence, and the team decided to turn it into a song that Pauline could perform, having been established as a singer in Super Mario Odyssey. Both Motokura and director Kazuya Takahashi credited Pauline's inclusion with helping many of their ideas take form.