5x26 - Dragon Ball Z: Dragon Box

Trunks returns to the future, in which the Artificial Humans have taken over, and is reunited with his mother Bulma. He then obliterates No. 17 and No. 18 with no difficulty. Previously, he had been no match for them, but thanks to his training in the past, the incredibly powered-up Trunks was without equal. A few months later, Trunks also easily dispatches Cell, when he comes after the time machine.