In Mario Tennis, Waluigi had come out of hiding after years of training to defeat his rival, Luigi.
Mario Party 3
In Mario Party 3, Waluigi had control of the Mischief Star Stamp. You could not use him in Story Mode.
Mario Party 4
Waluigi had become part of the available characters in Sotry Mode.
Mario Golf: Toadstool Tour
Waluigi entered the Toadstool Tournament in order to defeat Luigi yet again.