Luigi Numberone has an easy choice for who he'd shill for. It would pretty obviously be Nintendo. Owners and creators of the very series he comes from, Luigi would probably put on a play for them with his brothers and friends, reenacting one of his many adventures through the Mushroom kingdom. His 3rd journey would be a good choice, including plenty of fun locales, a few intriguing enemies to face, and a stupendously large airship fleet that would make for quite the action setpiece. He could even be his own stuntman, as he's still able to pull off all the moves necessary.
The best part is that it wouldn't even need to be that good to make billions of bucks. With that money, Luigi would probably just save it all; he has millions of dollars worth of gold coins over his career just gained from New Super Mario Bros 2 alone, already owns a well-sized house, and doesn't really lack for anything in his personal life.
The best part is that it wouldn't even need to be that good to make billions of bucks. With that money, Luigi would probably just save it all; he has millions of dollars worth of gold coins over his career just gained from New Super Mario Bros 2 alone, already owns a well-sized house, and doesn't really lack for anything in his personal life.