You can use G-Bowl App on an iPad 2 or later model or on a 5th-generation iPod touch or later model. Wi-Fi-only models, however, do not have GPS, and you cannot use the G-Bowl functions using GPS on them.
Added on April 8, 2016: The update of Ver. 3.4.3 has enabled the use of an external GPS unit (such as Garmin GLO, GNS 2000, etc). With a Bluetooth GPS unit, you can use all G-Bowl functions on any Wi-Fi-only model.