You see when she gets her wish on the core she says it in such a way that sends her through time and she names New Donk City after him later DK sees adult Paulene and takes her up a construction yard to talk. Mario sees this and due to a misunderstanding tries to rescue her.
This is laying the ground work for a crossover game between this and Kirby that will reimagine the Smash Bros series as a co-op action platformer with RPG elements.
Okay but I actually want that.
I realize in my sarcasm I just created the ideal design doc. Hell lets throw Sonic in so you can have a full four character party.
Oh it's gotta be full Everyone Is Here, just turn Brawl's Subspace mode into a full length RPG