I'd love them to do something like the old Wario Land commercials where you think it's a trailer for a Mario game and BAM! Wario jumpscare! It'd be such a cool homage.
As everyone has said, greed is definitely his most defining thing first and foremost, but Wario being so driven is something that defines him to me. He gets his ass beat in SML2 and decides that if he can't steal a castle... he might as well go...
I think he has many stand out features, his fatness, his strength, his greed, and how absurd he is.
But I think Nintendo makes him stand out about his encompasses.
Tatanga looks like funny and cute.
Yes, he could be a good Wario Land enemy or boss. We have Princess Daisy in Super Mario sports, racing and mini games videogames and in Super Smash Bros, and she only had an only one videogame like protagonist...