[Sombre]

I believe Mushroom Kingdom is overpowered, I was told Magoserium is overpowered, the non CBM version of Hoburg Kingdom is pretty much overpowered,... I would argue Haida Gwaii is also slightly overpowered and so is Sylvania, arguably.

There are others, have a look around. I try to avoid them generally speaking so I'm not an expert on them. Shovah actually might have better knowledge of such nations.