It's an area dependent feature. (like ventilation, predator protection and other features)
I can't use wheels because my soil is more of a clay and the wheels sinks when wet. It be like constantly getting a car wheel unstuck from mud (without the ability to use kitty litter). The skids glide over the mud like they would over snow. They work on dirt fine too.
Retractable wheels may solve your issue. It works like a lever and they aren't bad. Be careful on placement when installing.
(This not my coop or craftsmanship. Used to display wheels. There are lots of varieties)
There are also side wheels. These are good on small coops and don't require a lot of placement skill.
(not my coop but example)
Or elevated coop wheels
Best for large flocks
This one below is more like the skids on mine but still not mine
best for mud and snow
There are a variety of ways to make it move and predator proof but really it depends where it is and how many.
The 3 different tractor styles I have seen is the traditional shed (if it looks like a shed or box no matter how small it fits in this category), Ark, and hoop. Most displayed are the traditional shed coop but i'm partial to the ark for my area due to wind resistance for tractor coops.
*none of the coops pictured are mine. I just use google images.
