Found on sketchy, ad-heavy ROM websites with generic, auto-generated text. Safe Alternatives for Portable Tekken Tag Tournament 2
This is the most challenging step. You'll need to search for a version of Tekken Tag Tournament 2 that is confirmed to be a "PPSSPP ISO" or a "highly compressed" version designed for Android and PC. These are the fan-made conversions, so use specific search terms like "Tekken Tag Tournament 2 PPSSPP ISO" to find the correct file. The file will likely be a .iso file.
It isn't a perfect 1:1 port, but it is the closest you can get to playing Tag 2 on the go. It breathes fresh life into Tekken 6 and is a must-have for anyone who still carries their PSP or uses an emulator. Quick Specs & Details Base Game Required : Tekken 6 (PSP ISO)
A guide on for Tekken 6.