Can someone with a bachelor's degree teach at a community college, or are they required to have something more?
The basic answer is that it depends on the field. For example, here in California we have minimum qualifications called FSAs, which are written into the ed code. I'll answer the question based on California law, but I don't think it's terribly different in other parts of the US.
First let's talk about an example in an academic (not vocational) field. In my field, physics, the minimum qualifications are essentially a master's degree in physics, although certain closely related degrees are also OK. There is also a process for granting equivalency if you don't meet the FSA. In reality, when we hire for a tenure-track position we would not seriously consider a candidate who did not have at least a master's in physics, and we would strongly prefer someone with a PhD. We might consider someone who barely met the FSA if we were desperate to fill a part-time position, especially if it was something like the lab for a gen ed course and the person had the necessary technical skills. It's also sometimes necessary to go through the equivalency process as a formality in cases where the name of the degree doesn't exactly match what the ed code says, e.g., someone has a diploma that says "applied mathematics," but the FSA is "mathematics."
Community colleges also do vocational education. In those fields candidates must have either a bachelor's degree and 2 years of experience, or an associate's degree and 6 years of experience. For example, someone with a bachelor's degree in history and 2 years of experience in appliance repair would meet the minimum qualifications to teach appliance repair.
In general, the minimum qualifications are just the minimum. Hiring committees are not looking for a candidate who barely meeds the minimum qualifications, or who needs to go through equivalency.
Hiring committees for community colleges are usually going to count two factors as the most important: education and teaching experience. When someone gets a tenure-track community college job with a lower level of education, such as a master's degree, it's usually because that person has extensive teaching experience.