Developer Harry Stahl from Hastasoft a video showing how to add hints to Delphi XE5 Firemonkey using a utility unit he wrote. The video is in German but you should still be able to follow along if you need to or just download the unit and implement it. Basically how the unit works is that it hooks into TButton, TSpeedButton, and TLabel and ads hint functionality. There is a InitHintSettings function which you call to set up the hints and then you can set hints on the objects where you want them. It uses a TCalloutRectangle to implement the hints. You can customize the look and color of the hints by setting various TCalloutRectangle properties. Obviously since most mobile devices do not have a mouse this hint unit is targeted towards Windows and OSX desktops. A Timer and OnMouseEnter/OnMouseLeave events are implemented to handle the actually mouse cursor detection. There are probably some changes that need to be made to have this unit work under Delphi XE6 and AppMethod.
Head over and watch the video for yourself where Harry demonstrates the Firemonkey hints unit. And head over to his download page and download the unit.
Or download the Firemonkey hints unit from this mirror.