Superman vs. kaiju is tough to do generally because half the point of kaiju is that their monstrous size gives them a massive power/destructiveness advantage over their opponents, and generally Superman is not at that disadvantage unless they did something like Trigon in the JL/TT movie (which was not visually interesting, FWIW). Though now that I think about it, maybe they can apply the Doomsday concept and just scale him up in size.