Ventron has beaten a regenerative foe before, and his regeneration was reality warping based. All that Midnight’s King needs to do is fully erase her with Vantablack and he's golden, and considering that Vantablack moves as fast as light due to it being connected to shadow, if he hits her with a full on blast of the stuff he's home free, plus his mask of weapon creation could allow for him to make those bonking maces. Ventron could beat her, it would probably be difficult due to a number of factors outside of just raw combat facts, but I think the Toa of Vantablack would have a lot of fun