The Type 99A2 (the official name is actually ZTZ-99A) won't be available for export right away, as it is currently the most capable platform their ground forces have in service and their only vehicle designated as an "enhanced 3rd generation" tank. Granted, there was a rumor that their next-generation MBT prototype has been assembled since 2014, so the status quo might change.
That leaves the PA the choice between the Type 99A1 and the MBT-3000 for now (assuming that their top brass is looking to buy Chinese), both of which should be pretty comparable to other 3rd generation MBTs in terms of performance and logistics. The only hurdle would be the tanks' tolerance in Pakistan's desert terrain and heat, and also potential export limitations on their German-derived engines (although the MBT-3000 should have a Chinese engine by now).