As some of us (if not all) know, Kara Zor-El and Mon-El are from close planets (are they?) hence the super powers. In the Supergirl episode where Supergirl breaks into the mother-ship to save Mon-El and Lena, she was able to defeat the guards easily. To my understanding, she shouldn't have been able to, since they are also Daxamites, having super-strength. Rhea has it. Why is that? Is it because they were on the ship all the time, thus not being exposed to the sunlight, or is there another explanation?
Kara has super strength. So do the Daxamites, but as is shown when Mon-El is being tested by Winn at the DEO, the Daxamite level of strength is less than the Kryptonian equivalent. They are also missing a number of the powers Kara exhibits, including flight and freeze breath.
So Kara is stronger, and she has also trained with her sister Alex in a variety of fighting styles (in a room using small amounts of Kryptonite radiation to bring Kara down to a more human level of strength). These facts combine to make her suitably dangerous even to (presumably) well trained soldiers/guards with a level of super strength.