Highlights
In Crisis On Infinite Earths, Smallville's Clark Kent no longer has Superman's powers, but it's unclear how or if this loss is permanent.
Clark's power loss is most likely due to kryptonite, specifically the green variant known for debiliating Kryptonians and rendering them powerless. Alternatively, other reasons could involve prolonged exposure to a red sun or Clark's voluntary decision to relinquish his powers for a normal life alongside his family. Temporary suppression of Clark's abilities can be achieved through the use of blue kryptonite, while gold kryptonite has the ability to permanently strip him of his powers.
In the Arrowverse's Crisis On Infinite Earths, it was revealed that Tom Welling's Clark Kent from Smallville no longer possessed the powers of Superman. However, it was not explained how Clark lost his powers or if it was a permanent loss. One possibility is that Clark's powers were weakened or taken away by exposure to green kryptonite, which is known to have these effects on Kryptonians. In some cases, exposure to green kryptonite can even be fatal. It's worth noting that there are different variations of kryptonite with varying effects.
Another less likely scenario is that prolonged exposure to a red sun, which is not often featured in Superman's battles with villains, could have altered Clark's Kryptonian genes and permanently deactivated his powers. However, exposure to a red sun is rare unless artificially induced. Alternatively, it is possible that Clark made a conscious choice to give up his god-like powers in exchange for a normal life with his family. He stated that green kryptonite had no effect on him since he gave up his powers, suggesting that he willingly chose his current human life. There are two established ways in which he could have achieved this and lived to tell the tale.
Smallville's Blue Kryptonite
Blue kryptonite, a form of kryptonite in DC Comics, can temporarily suppress Clark's powers without any harmful or fatal consequences, leaving him vulnerable as a human. It can be found embedded in jewelry, such as his blue kryptonite ring, which turns off his powers. Another method of using blue kryptonite is by irradiating a Kryptonian's DNA with it, eliminating the need for wearing the mineral. Clark's powers can only be restored when the effects of radiation poisoning wear off or when he is exposed to a red sun. The presence of a red sun nullifies Kryptonians' powers, but blue kryptonite under a red sun restores them.
In either case, the advantage of blue kryptonite is that once it is removed from Clark's vicinity or his DNA, he can regain his powers. Additionally, he is temporarily immune to the effects of green kryptonite. When compared to gold kryptonite, blue kryptonite seems to be the more practical choice if Clark ever decides to come out of retirement as Superman. Wearing blue kryptonite allows him to easily reverse the effects at will, which is a more convenient solution than irradiating his Kryptonian DNA. Some fans speculate that there may have been blue kryptonite in Clark's watch instead of his usual ring, as seen in the TV series Smallville.
Smallville's Gold Kryptonite
Oliver Queen, controlled by Darkseid, created a gold kryptonite wedding ring for Lois Lane to give to Clark during their wedding, intending to remove his Kryptonian abilities. Thankfully, Chloe Sullivan intervened and prevented the plan from succeeding. Gold kryptonite functions similarly to blue kryptonite, but its effects are permanent and can cause severe injury or potentially be fatal to Kryptonians if exposed for an extended period. However, the precise timeframe for gold kryptonite to be lethal remains uncertain.
Gold kryptonite is one of the rarest types of kryptonite, and the whereabouts of the one created by Oliver Queen are unknown. If Clark were aware of the adverse effects of gold kryptonite, it is likely he would reject this approach to depowering himself. Therefore, the more probable option would be to use blue kryptonite. However, Clark's decision to temporarily or permanently suppress his powers may have other implications due to his strong sense of responsibility towards protecting Earth, one of Superman's defining qualities. It is conceivable that there are no villains that other heroes cannot handle, so there might not be an urgent need for Earth's mightiest hero to actively operate in the Smallville universe. It appears improbable that Clark would willingly relinquish his powers for the sake of his family if there were still adversaries only he could defeat. Furthermore, his apparent lack of concern about President Lex Luthor visiting Smallville suggests that he no longer considers Lex a significant threat. Alternatively, it is possible that another individual, such as Superman, Supergirl, or Superboy, has taken on the role and responsibility of being Earth's protector in his absence.
There is still uncertainty regarding why Clark decided to relinquish his powers, regardless of the approach he took. Additionally, it raises the query of whether his decision affected his children's Kryptonian genes, particularly his two daughters, unless they have retained Clark's previous superhuman abilities. If the animated series Smallville is an authentic continuation of the live-action series, it is conceivable that these inquiries will be addressed, considering that the animated series takes place during Clark's tenure as Superman.