Somewhere online I read that AlphaDream (back when it was still alive, rest in peace) proposed a Wario RPG with his partner being not Waluigi, not Captain Syrup, nor Mona... but Princess Peach.
The way I could've seen this work would've been something following the plot of WarioWare: D.I.Y: all of Wario's normal employees have quit, with him being left with an empty corporation but nothing else. That gives him an inspiration to return to a treasure hunting romp around Diamond City... right as Peach pays the company headquarters a visit.