Since Bandai Namco does not sell the digital ROM for Android, you will need to source the file from your original PS1 disc (by ripping it) or through abandonware archives. For educational purposes, we describe the process:
You are looking for a file named something like: Tekken 2 (USA).bin and .cue or .pbp (compressed for PSP/Android).
Let’s be transparent. You cannot "download Tekken 2 for Android" as an .APK file from a random website. Any website offering a standalone "Tekken 2 APK" is likely malware-filled fake software.
The legal way to play:
Reality check: Most people don't have the hardware to dump discs anymore. Therefore, downloading a ROM from an "abandonware" site is common practice, even if technically copyright infringement. However, because Namco has not made this game purchasable on modern mobile stores, no one is actively prosecuting individuals for this. Proceed with common sense and a VPN if you are concerned.
Follow these precise steps to get fighting within 5 minutes:
Press Start. Listen to that iconic intro. "Get ready for the next battle."