i've always thought that since both of their designs are supposed to resemble Germanic mafia-men, and Wario's games are hyper-violent beat em up puzzle games, Waluigi's games in comparison would be experimental shooters, kind of like killer7, with a cartoonish colorful but also bleak and somewhat uncomfortable art style. Gameplay and story would also be highly subversive, being sort of like the Belgian comic Dr. Cataclysm which have a lot of serious and usually dark subject matter but done in such a goofy way that you forget what it's about. In my opinion that'd really fit the Waluigi we know, goofy and disproportionate but also genuinely intimidating and very violent.
Mario Pinball, Wrecking Crew, and Dance Dance Revolution: Mario Mix are all games that Waluigi can hijack and become the main star of. He has a pinball track in Mario Kart, he has an excavator kart referencing Foreman Spike, a Wrecking Crew song plays during Waluigi's battle in DDR, and he seems to be really passionate about dancing.
I imagine a Waluigi's official Nintendo videogame like a Wario Land but with the difference of Waluigi's moves and atacks and videogame theme, the Waluigi's moves and atacks would be stranges, crazy and very funny and Waluigi's videogame theme would be about make villian things inside of want money.
