If it's an SNK guest character my bet is on a popular Samurai Shodown character. I hear the reasons why Geese was brought to Tekken was not only because Harada is a massive Geese fan but King of Fighters is extremely popular in places like China, South Korea and some Latin American countries. If the decision is going to be on similar lines I just want to ask some of the Latin American folk in here, is Samurai Shodown still popular or was it popular in your country? If so who were the most popular characters? This will give me an idea on who to expect if it is going to be a Samurai Shodown character.
Not from Latin America, but answering anyway:
Some of the most popular (and most recognizable) SS characters are:
Haohmaru - The Ryu of the series. You might expect him to fit the classic samurai archetype a bit better, but he's way less disciplined than someone like Mitsurugi. His attacks tend to be wild, with some of them having almost a street-brawl feel. He'll whack his opponent with his drinking gourd, for example. His projectile attacks form a big part of his gameplay. Because of his similarity in appearance, and because both of them are the poster child of their respective series, fans have long wanted to see him square off against Mitsurugi. Oh, and I shouldn't neglect to mention that both Haohmaru and Mitsurugi were inspired by the real-life
Miyamoto Musashi. They're practically long-lost brothers!
Nakoruru - Nakoruru is a peaceful, nature-loving girl. So if you think of Talim, you're half of the way there. She's also part of the
Ainu people, and to my knowledge, she's the only representation of their culture in a video game. She fights with her hawk (Mamahama) supporting her, and in some games with a wolf. Her other most iconic (and annoying) move is a sudden dash forward along the ground that targets her opponent's feet.
Genjuro - Don't let the pink fool you. Genjuro is a total badass, and Haohmaru's arch rival. The giant scar on his back (a bit hard to see in the linked picture) is from a duel he lost to Haohmaru. His swordplay is aggressive and brutal. He has a wide range of moves, which include an anti-air, a rekka combo, throws and projectiles. His moves also have a
hanafuda theme, which might seem random. But it definitely has visual impact!
Hanzo Hattori - Inspired by the real-life
Hattori Hanzo, this guy is of course the ninja of the series. Aside from having an incredibly cool design, his moveset is incredibly versatile and has changed a lot over the years. He can throw fire projectiles and shuriken, teleport, turn into a tree stump, and (in rare instances) even breath fire. His most iconic move is his izuna drop, in which he grabs his opponent, jumps into the air with them, and brings his opponent head-first back to earth in a fiery explosion. He shares some moves with an American ninja:
Galford. But between the two of them, Hanzo is definitely the more popular. Galford has a nice doggo though. Hanzo would make a great rival for Taki!
These are the characters most likely to be guest characters. Unfortunately, the chances of any of them joining are relatively low, since they just don't have the worldwide fame that other characters (Geralt, 2B, Darth Vader) have.