Jenilkanani,
If y-value is zero, when you mouse-hover the axisX line at the corresponding x-value toolTip will be shown. Check the screenshot below. If the y-value (zero) is not present in first dataSeries, you can set toolTip.shared to true to show the zero value in toolTip.
If this doesn’t solve your requirement, kindly create a jsfiddle, so that we can look into your requirement properly and help you out.