Most people know Waluigi doesn’t have his own game or had any role in a main series Nintendo game, but I don’t think some people understand how bizarre Waluigi’s situation really is.
He hasn’t just ‘not had a role’, we don’t see him at all. He’s never mentioned, not by his ‘bro’ Wario in Warioware, not by his nemesis Luigi. Not by anyone.
Outside of spin-off sports titles, second party games and Smash bros. there are a few hints of him (from my knowledge)
In Game and Watch (not Warioware!), he’s a boxer for a mini-game
In Thousand Year Door, you can get a purple hat and sleeves alt.
In Super Mario maker, he’s a playable mushroom power-up
Waluigi has been in over 50 games and the only sports game in recent memory I can think where he wasn’t playable was Mario kart 7 and even then he had his own course ‘Waluigi Pinball’ in it. Since his creation, there hasn’t been a year where Waluigi has not appeared in a game. 16 years straight of consistent Waluigi right there, folks.
Waluigi has had serious screen time. He has had more voice acting, lines of dialogue and more information dropped about him then some main characters in other games. He’s had considerable parts in the tennis and golf games, with cutscenes and large roles alongside Wario. We all know his character, we’ve seen him around everywhere.
So why have we never seen him in a Nintendo game? Not even as an npc whose only line of dialogue is ‘wah’. Not even as a passing Easter egg? Not even as a poster in the background or in a single line of text from a toad hinting to him?
Its just so strange. It makes him feel like a mass hallucination that only appears when you say the words ‘sports’