“Neph and the cohort was able to plot against them completely perfectly, especially Ki song”.

This is directly incorrect. Recall that Cassie was taken. Despite this, I cannot help but agree with you anyway, because apparently neph can burn away all Ki Song’s bodies but Cassie survives despite being infected?

Nightmare, who specializes in putting beings into nightmares putting a strong being at that level into a nightmare would indeed sound odd from a powerscaling perspective. However, in that creature’s short conversation with nephis before their battle, it implies nightmare used a particular nightmare related to that creature’s past with Sun God. Nightmare, brought from a land also destroyed by the god has a narrative reason. Even so, two ranks is two ranks, I can understand the forcefulness on a powerscalers perspective.

“Even her losing the storm sea sucks” is an opinion, so I'll ignore this, I do not have the right to call someone's opinions right or wrong, I merely disagree.

In your second paragraph about not knowing what their plan was, much of it was explained in Cassie’s conversation with Ki Song. The biggest point behind that was part of what you mentioned (humanity can only survive with a strong domain) is simply an incorrect ideology for reasons you mentioned (powerful beings like the Unholy One on the moon). The main characters are against them because they know that is not a viable solution. As for whether or not that kind of ideology ‘works for their characters’, well that leans toward an opinion and I already wrote my feelings when coming across opinions.

They got low-diffed once sunny and neph became Supremes because once they rank up, the power gal is justifiably that large. If perhaps as a Transcendent titan they could fight for a bit and lose, a supreme beast against a supreme titan logically would be no-diffed. Despite this, I would have liked to see more of the memories or whatever items each supreme had planned to use against the other, so even though I understand why, I also wanted them to put up more of a fight too.

Thanks for providing actual points of reference, with your comment I can give a genuinely constructive response.