Waluigi appears to be Luigi’s evil counterpart and his arch-rival as well.
He first appeared in Mario Tennis 64 along with Wario who becomes his partner and unlike Wario, he enjoys harassing Luigi getting into a rivalry of sports and competing in Mario Party Games by beating him.
He normally appears antagonist in some sports like teaming with Wario to antagonize the Mario Brothers, but like Wario becomes more of an anti-hero in some games like Mario Party Series and becomes more of ally to Mario and his friends as he is still on bad terms of relationships with them and however he has a crush on Princess Daisy that she refuses to admit it.