relocating stove

I want to Move my stove 15 feet from it's original location. Can i simply run a flex pipe of some type from the stove's original gas shutoff valve location to the new location? This would entail running the pipe below the hot water heater and under the kitchen sink. Any code violations or restrictions in this move?

I don't think a flex that long is made, and I doubt that you would be wise to run any kind line under a water heater. Is access under the floor a problem or are you just looking for a super easy way? You should run additional black pipe under the floor to the desired location. Unless you are fully capable of working with gas, you should call a pro. A bad waterpipe connection will just leak water, but a bad gaspipe connection could ruin you whole day.