It works without requiring another switch. You do have to have the SmartThings hub. The switch talks to the hub, the hub passes the request on to the smart bulb. 
Remotec also has an eight button battery operated device which is worth considering. It’s about the same size as a regular light switch. Each button can be tapped, double tapped, or held so you end up with 24 controls from the one device.
And the two smart battery cover devices can also be used standalone without being placed over an existing switch, so those are additional options.
So just comes down to what you like the looks of and how many different controls you need from the one device. The Cooper is popular because it looks exactly like a regular light switch.
All of these and more are discussed in the button FAQ. (This is a clickable link)