Dragon Ball's immortal villains vary drastically when it comes to Power Levels, some being much stronger than others.
Comic Book Resources on MSN

The most useless Z-Fighters in Dragon Ball Z

Typically, either Goku does all the work in DBZ, or the anime only values the Saiyans and Piccolo, leaving the human Z ...
Ultra Instinct is the ultimate technique in Goku's arsenal, but there are a few transformations that are even stronger.
Demon Slayer avoided Dragon Ball's biggest power scaling problem by keeping its heroes human, vulnerable, and limited, making every fight count.