The best experience still comes from actual hardware. If you own a PS Vita (1000, 2000, or PS TV), you can mod it (homebrew) to run backup copies. This is legal if you own the original game.
Steps:
Pros: Zero lag, full dual analog sticks, physical buttons, online play (via community servers). Cons: Requires technical know-how; you need a physical copy to dump legally. Street Fighter X Tekken Psvita Rom
Currently, there is no stable Vita emulator for Android. However, using a hacked PSVita TV (PlayStation TV) connected to a monitor is often better than native Android emulation. The best experience still comes from actual hardware
For the uninitiated, SFxT is a 2D tag-team fighter where players choose two characters—one from the Street Fighter roster, one from Tekken—and battle it out using a unique "Gem System" and "Pandora Mode." The Vita version retained the full roster of 55 characters (including fan-favorites like Mega Man, Pac-Man, and Toro the cat as PlayStation exclusives) and all the strategic depth of its console siblings. Pros: Zero lag, full dual analog sticks, physical
The game's story mode features an original narrative that brings together characters from both franchises. The story follows the characters as they compete in a martial arts tournament, only to discover that the true purpose of the tournament is to gather energy for a powerful being known as "The Chaos."