When we say Potter universe, are we just talking about the wizards or everything in their universe? Because they also have dragons you know, as well as giants and basilisks and stuff. Plus even if it's just the wizards, they have a variety of spells they can use. They might even be able to simply immobilize Godzilla, or force an Imperio on it.
All I'm saying is the potter universe is too vast and too versatile. With way more options than our human military.