What to do with Metallo?

[scary harpy]

The thing is, if we’re using Kryptonite Man, and I like the New 52 K-Man Clay Ramses who is a wifebeater, Metallo and K-Man relying on Kryptonite feels redundant.

Then ditch K-Man? If two characters having the same thing is redundant, then the more obscure character should be the one to change somehow. Metallo is just the better known villain. And I don't think it's that redundant either.

Don't ditch any villain. Superman needs more foes not less.

Is Metallo overused? Could that be his problem? Or does he just need to be used better?