You ever notice how Luigi's mansion 3 is similar to the DK DLC from Mario + Rabbids

[Mymy64]

(hot take I know but bare with me)

-Both are split into 4 areas
-Both have an overpowered character
-Both have 7 enemy types that don't change throughout the game
-Both have a character that steals an important in which they have to fight enemies to get it back

 

[Xiahou Dun]

Seems like a bit of a stretch, no offense.

 

[Biddybud]

Conclusion:
Luigi's Mansion is a Rabbid.
E.Gadd is Biggest Fans grandpa, who is also a Rabbid.