Every Arrowverse hero ranked from weakest to strongest
Superman (Supergirl version)
The Man of Steel may not have been a main character in Supergirl but since he is one of DC Comics' most iconic characters - and he played quite a major role on the show in its early seasons - we're choosing to include him here. Yes, Tyler Hoechlin when on to play an alternate version of the character in Arrowverse-adjacent series Superman and Lois, but right now, we're just discussing the primary Arrowverse version of Superman.
What is there to say about Superman that hasn't already been said? He's one of the world's finest heroes, and a powerhouse at that. Stronger than a locomotive and faster than a speeding bullet, Supergirl's Superman was as durable and fast as you'd expect. He could also fly through the skies of Earth with ease, utilize cold breath when needed and employ a very different version of heat vision than we're used to (it was blue).
While Supergirl did draw occasional criticism for repeatedly having him fall victim to one too many villains' evil schemes (he wasn't strong enough to overpower the effects of Myriad in season 1 or Rhea's mind-controlling Silver Kryptonite in season 2), the Arrowverse's Man of Steel is still one of the most powerful beings on Earth-38 and Earth-Prime.
There is just no coming close to a Kryptonian... unless, you know, you're another