He becomes Number 10 in the world before he becomes Masquerade's henchmen when he's exposed to the Silent Core. He reappears as Masquerades henchman, along with Komba, and battles Julie and Shun. He loses, however, he still remains an antagonist. As Masquerade's henchman the others often make fun of him since he is the only one in double digets and is lower ranked than the rest of them, especially Komba
Later, when Julie attempts to bring him back to his senses with a battle, he nearly sends Julie and Gorem to the Doom Dimension but pulls out the card just in time after seeing the toy he had given her when they were young, he still defeats her but right before Gorem is sent to the Doom Dimension he takes out the Doom Card. He is then freed from Naga's control and Billy explains to the Brawlers how he first met Naga.
His Cycloid is sent to the Doom Dimension by Masquerade to make his Hydranoid stronger and is presumably reunited with Cycloid around the same time as everyone else's.
He agrees to help everyone stop the minions of Naga, slowing down Rabeeder but not stopping her from getting closer to the city. He returns to help Julie and Nene fight the Subterra-Haos Tricloid, resulting in him and Julie forming a girlfriend/boyfriend relationship.
He appears again when battling against Prince Hydron with Julie and Ally,He and Ally has a friendship when Ally meets someone that same as his.
- Subterra Cycloid(Guardian Bakugan)
- Subterra Legionoid(Trap Bakugan)
- Subterra Verias
- Subterra Moskeeto
- Subterra Goblinball
- Subterra Vandarus(Gave to Klaus)
Although Billy has been shown to be very skilled and ranked very highly, most of his battles have been losses. Most of his battles have also involved Julie Makimoto in some way, with five out of seven battles being against her or along side her.
|Prince Hydron(Tag with Tricloid,Jewels,and Chana Lee)||Win|
|Prince Hydron(Tag with Julie Makimoto and Ally Fujisaki)||Win|
|Ace Grit & Ally Fujisaki(Tag with Julie Makimoto)||Lose|
|Tricloid(Tag with Julie,Mira,and Chana Lee)||Win|
|Mylene Pharaoh & Lync Volan||Win|
|Volt Luster||Lose(letting Billy become a vexos)|