The best Billy build in Zenless Zone Zero is a pretty straightforward one, centred around buffing the gun-toting cyborg's crits and ability to proc the powerful physical anomaly, Assault. He might not be the game's greatest attack character, but physical is a very strong attribute for damage-dealers, and best of all, Billy is free when you start the game.
If you pre-registered and got Corin free, too, but aren't a big fan of her chainsaw, Billy might serve you better. He's got a pretty unique playstyle among other agents, focusing as he does on blasting foes at range and hitting lots of enemies at once with his chain and dash attacks.
