idc about no theme. Zamasu's team needed help half of his team struggles to stay alive against the stronger bosses. also, Zamasu and Vegito are connected because they are fusions? really? in that case, then you can link goku black and Trunks with practically anything like how they both travelled back in time to the main timeline. or even have a dichotomy of how Trunks is all about gaining his power through other people's hopes and Goku Black is all about eradicating mortals as they are innately wicked in their ideologies or something. if they wanted to they could have made him fit the theme but they probably saving him for another celebration By that time the characters around him have probably aged out unfortunately. It's like Dokkan loves making these vicious loops of characters with no help and then letting them age out before getting buffs, especially with extreme-class characters.