T-Rex: Waluigi, whose name meant "Bad Luigi", stared in shock!

Narrator: WALUIGI - a Fan Fiction

T-Rex: He'd just met LUIGI, whose name meant "Luigi". And Luigi was his EXACT OPPOSITE! Where Luigi was good, Waluigi was bad. Where Luigi was afraid of ghosts, Waluigi was fearless in the face of supernatural evidence that consciousness can survive death. Where Luigi was sexually ashamed, Waluigi was bold, confident, and always carried a single long-stemmed rose, just in case.

Utahraptor: It sounds like they're not going to get along!
T-Rex: Oh, on the contrary!

T-Rex: By definition, everything Waluigi didn't know, Luigi did - AND vice versa. Between the two of them, they had the sum total of ALL POSSIBLE KNOWLEDGE in their heads. So by teaming up, the two of them were able to solve all sorts of problems, taking breaks only to race karts together.

T-Rex: And similar to how the President and VP aren't allowed to be on the same plane in case it crashes, Waluigi and Luigi weren't both allowed to be in Smash.
Off panel: So THAT'S the reason.
T-Rex: RIGHT?? As you can see, my fanfic satisfies everyone