Well, I have done calculations on this, here is your answer! I will include every website used in this as well.
Reference
I used a part in the Daydream Believer trailer where the Common Wubbox launched Gobbleygourd into the stratosphere as a reference. (https://www.youtube.com/watch?v=OIvUa-t8Kgs&ab_channel=MySingingMonsters)
In a video on the MSM account, a questioned is answered about how strong the Wubbox is. It was stated that Gobbleygourd was shot into "the Monster World's stratosphere" with hardly any effort. It isn't known how big the Monster World is, but as an example, I'll use the Earth's.
Speed
It took 15 seconds for Gobbleygourd to stop falling. Assuming it stopped going up at that time when it reached the stratosphere, we can use that for reference. From the surface to the stratosphere, it is 50 kilometres in total. Using SDT, we can divide the distance (50km) by the speed (15 seconds) which gives us a result of 7456 miles per hour, crazy right? I converted this number into kilometres per second, which gave me 3.33 kms.
Simulation
I used an asteroid simulator (https://neal.fun/asteroid-launcher/) to calculate how many kilotons of TNT this would be equivalent to, it turned out to be 6 kilotons. I then put this into a nuke simulator.(https://nuclearsecrecy.com/nukemap/)
Results
For moderate blast damage, it gave 1.28km. However, for light blast damage it gave 40.5km.
Conclusion
A town is 0.5 - 1.3km in size, so in conclusion, a small punch from a Wubbox could cause an entire town to collapse. Sorry, but I can't get the calculation for a full powered punch currently, but if you could, I'd be happy for you to solve how powerful Wubbox truly is, but for now, the answer is Town+.
