I can't be the only one who loves Waluigi's story arc. He went from a minor character to an all out supervillain. Since I have nothing better to do I decided to make a timeline.
Smash 5 Trials[]
Waluigi loses the trial and Wario turns him into an assist trophy
Waluigi's Time[]
Waluigi unlocks his rejection powers and attempts to join Smash, but when he got accepted he loses his powers and gets rejected again which regains his powers
T Pose[]
Waluigi poisons the kingdom with a T Mushroom
The Mario Cafe[]
Waluigi gets himself rejected by Toad
Mario SAW[]
Waluigi invites everyone to a party to get rejected, but Mari accepted his message, he kidnaps Mario (and Luigi) in order to make Mario hate him.
Mario the Scam Master[]
Wario finds Mario stuck and helps him in exchange for beng his new scamming partner. When he was about to throw Luigi into the water, Mario fights for him, reminding him of Waluigi. He then goes on a quest to take him home.
Mario Carnival[]
Bob mentions that Waluigi went insane and Wario went missing, making scamming a lot easier