VERY few motorcycles have automatic transmissions, and those that do are usualy of the centrigugal clutch type. The ninja 250 is not one of them, and only comes in one trim level, which is 6 speed, and a variety of colors.
Many scooters have automatic transmissions, the term scoter, doesnt refer only to the small tiny ones but also larger more expensive models. You can get scooters with cargo capaity and top speeds supassing 115mph to be driven on freeways. What makes a scooter a scooter is the riding position.
The only bike i know of that comes close to having a true automatic transmission is the yamaha FJR1300ae with a computer controlled, and actuated clutch, and mechanically shifted gearbox. There is no clutch lever on this bike, however, the operator must push a handlerbar button to tell the biek to shift up or down when driving it. (you can also use the foot lever to tell it to shift.)
An automatic transmission as are found in cars is a large complicated object that typically doesnt fit in motorcycles, the transmission in the fjr, is the same transmission foudn in the manual version, but has the addition of electronic solenids to operate it in place of human actuated levers