Emergency Flashers 2
Almost all Kawasaki Motorcycles made for street riding come with a hazard button, but (not surprisingly) the 250 doesn't. However, this is an easy mod and pretty cheap.
What you're going to do is swap your left hand control pod for one that was used on various Kawasakis in the late 90s-early 00s. The original part number was 46091-1716, which has been superseded by #46091-1857. Your best bet is to search for "Kawasaki + left" on eBay. You can do a "Where does this part fit?" search on Ron Ayers to see the various models that came with this part to aid in your search.
All you have to do is remove your left control pod and replace it with the new one. The connections are under the tank, left side, right next to the ignition switch wires. You will have to snip a zip-tie. If you have small hands, you can try to disconnect the control from below the tank, but you should probably count on removing the tank.
Then, unplug the left control, snip any zip-ties, unscrew the left control from the bar, remove the choke lever, swap, and reinstall.
The red button seen here is the hazard button.