I'm assuming Imu is a CoC master. Gunkmu might fuck L & L up by wifi diffing them out of their forms and that's how they learn to deal with it?
I think CoC coating is one thing, but in my opinion the CoC skill tree goes much deeper. That suppression quirk of CoC might be it's actual super power.
Hence Brook might be needed to disturb Imu's control. It's when they can go all in and hit Gunko with the most brutal overkill in op's history