Street Fighter X Tekken was released in 2012. The game features from both the Street Fighter and Tekken franchises, along with some other random characters (like Pac-Man). Several Final Fight characters appear in the game: Poison, Hugo, Rolento, Guy and Cody. This was the second time Poison had ever been made playable (the first was in Final Fight Revenge) and it was also the first time Rolento and Hugo had been seen in a new game in a while. You get to pick two characters, and can swap between them during a round. However as soon as one character is knocked out, the round ends.
Poison's partner is Hugo, whilst Guy is with Cody. Meanwhile Rolento gets...Ibuki? There was hope that Rolento was going to be teamed up with Sodom, especially after a trailer for the game had this little easter egg in it, but in the end it wasn't to be (Heihachi was given an alternate costume to make him look like Sodom, at least). The story is that Rolento needed someone who was good at infiltration, and he ends up teaming with ninja girl Ibuki, who was originally from Street Fighter III. In addition to the Final Fight characters, there is also a Final Fight stage called "Mad Gear Hideout" which features cameos from the likes of Edi. E and Haggar.
Street Fighter X Tekken was a very controversial game when it was released. Within days, hackers found out that there were a bunch of practically finished extra characters on the disc (including Guy and Cody), who were just locked away. Turns out that these characters, despite them being on the disc, were going to be released later as paid for DLC. This caused an uproar, as did the gems system the game featured (which included gems you could pay money for) along with the Xbox 360 version advertising a feature it didn't actually have. Shots were fired, people got angry, Capcom's Better Business Bureau rating dropped and the game under-performed at retail. Whilst it sold over a million copies, Capcom had previously announced they hoped for it to sell over 2 million, and for a cross-over game between the world's best selling 2D and 3D fighters, sales were poor.
Players found a lot of bugs in the game, such as easy infinite combos and a glitch where Mega Man would fly into the sky. Capcom later released a patch, which updated the game to version 1.04. This fixed most of the glitches, but added a major new bug which involved Rolento. If Rolento's stinger move (the move where he throws a knife) hits a projectile thrown out by the opponent, the game would freeze. This was the point where the game became a laughing stock, and as time went on it was dropped from tournaments. Capcom later had to release another patch which fixed the Rolento glitch, and were rumored to have fired several play testers. Another patch was released later which was well-received by players, but the damage had already been done.
Street Fighter X Tekken is available for PC, Playstation 3 and Xbox 360. These versions have a character pack you can purchase, which adds several extra characters to the game, including Guy and Cody. The game was later released for the Playstation Vita, which has the extra characters added by default. An iOS version was also released, which does not the full roster of characters -I know Hugo and Rolento are in this version, but I don't know about the other Final Fight characters.