OEM uses offscreen energy and offscreens tdk (probably not a real thing, but i wouldn't be surprised if OEM could unironically make it a real thing or whatever [i'm not gonna read the actual page] so yeah)

I'm tired of using Fictional and Total Mimicry in most of my polls, I'm running out of ideas, but I think this will be a decent fight since Darkest Knight also have Omni-Energy Manipulation.

Omni-Energy User would use Anti-The Darkest Knight energy that would probably negate The Darkest Knight and one shot him.

Can they actually do that?

Yes.

Just like how Liebe developed Anti-Magic energy to combat Magic, they can develop anti-Darkest Knight energy to combat The Darkest Knight