
I love how in dbz certain charaters were only made as a way to show the z fighters growth pass the previous threat
Raditz shows up setting the new goal of strength to achieve and the z fighters train and the saibamen are equal to raditz and the z fighters easily defeat them (except for yamcha😆) showing they're now above raditz.
Vegeta is the main antagonist of the saiyan arc and cui is equal to his power of 18,000 and vegeta easily defeats him showing that he's stronger than when he was on earth.
Frieza is the main villain in the namek arc and his mecha form is confirmed to be stronger compared to him on namek and king cold is said to be equal to frieza in power and trunks kills both of them and goku arrives showing he's on the same level as trunks.
Cell was the main threat in the android arc and dabura is said to be equal to him and he was easily defeated by majin buu and goku stated he probably could have beat buu meaning cell is a nonfactor to him now in the buu saga.