Bill Kouzo is Dan Kouzo's father and Barbara Kouzo's husband, residing with his family in Los Volmos. He shows care for Dan through practical gestures like leaving food money when away. Initially, Bill and Barbara maintain a measured perspective on Bakugan. This changes when Kravitz, posing as an anti-Bakugan activist, visits them. Hearing their balanced views, Kravitz uses AAAnimus technology to forcibly activate Drago, causing significant damage to the Kouzo house roof.

Following the incident, Kravitz escalates efforts against Bakugan, deploying devices that trigger uncontrolled Bakugan activations across Los Volmos. Influenced by these events and Kravitz's manipulation, Bill and Barbara demand the Awesome Ones surrender their Bakugan. They join community protests supporting Kravitz's campaign, leading to the team's Bakugan confiscation. Later, when a satellite threatens Los Volmos, Bill witnesses Dan and Drago destroy it to protect the city. This pivotal moment shifts his perspective, prompting him to reject Kravitz's propaganda. He actively participates in tearing up anti-Bakugan fliers, signaling renewed acceptance of Bakugan in the community.