"Wakka (ワッカ) is a twenty-three-year-old professional blitzball player, characterized by a long reddish-orange quiff, being tall and muscular in appearance, and a Besaid Island accent. As such, he uses such speech-mannerisms as saying "brudda" for "brother" and sometimes finishing sentences with "ya?" His name means "water" in Ainu. In addition to being one of Summoner Yuna's guardians and childhood friends, he is captain of the Besaid Aurochs, a blitzball team that - as of the beginning of Final Fantasy X - went twenty-three years without winning a single game. He uses blitzballs as his weapons in battle, making him the only character who can reliably hit flying enemies, as well as making him and Lulu the only characters who can attack physically at range. Wakka is also one of the three players that can fight underwater, along with Tidus and Rikku.
Wakka seems somewhat socially conservative, dependent on others and on the rules (such as Yevon's teachings) for his decisions. He lost his younger brother Chappu to Sin, an event he never fully recovered from. He forms a close brotherly relationship with Tidus, partially fueled by his resemblance to Chappu, though Lulu constantly has to remind him that Tidus isn't Chappu. Nevertheless, Wakka gives Tidus his signature weapon which he previously gave Chappu.
As a devout follower of Yevon's teachings, Wakka believes that anyone who doesn't believe in Yevon, like the Al Bhed, are evil heathens, and is staunchly against the use of machina, though he also develops a more personal grudge against both for the roles they played in Yuna's kidnappings during the pilgrimage. Also, Chappu had used a machina weapon when he was killed by Sin, which compounded his hatred (Yevonite children are taught that people who don't follow Yevon are evil, and are killed by Sin as punishment). Due to this, Lulu and the others try to keep Yuna's mixed Al Bhed heritage a secret from him. He was disgusted when he found out that Rikku was an Al Bhed (ironically, he did not immediately notice her heritage upon first meeting her). However, he begins to question both his faith and his grudge when he discovers Yuna's heritage, and that the Al Bhed kidnapped her to prevent her from inevitably dying upon her defeating Sin. By the time Yevon's true colors are exposed to the world, Wakka denounces his prior beliefs entirely.
Six months after the events of Final Fantasy X, he marries Lulu. In Final Fantasy X-2, he becomes a father to her baby, Vidina, a name thought up by Wakka. "Vidina" translates as "future" in the Al Bhed language, and is Wakka's declaration that he has let go of Yevon's teachings, which were biased against Al Bhed, and even part Al Bhed such as Yuna.
A younger version of Wakka makes a cameo appearance in Kingdom Hearts on Destiny Islands as a friend of Tidus (also younger) and a sparring partner who can be engaged in battle, fighting with a beach ball that resembles a blitzball. He makes a smaller cameo in Kingdom Hearts: Chain of Memories, and receives only a fleeting mention in Kingdom Hearts II. In Kingdom Hearts, he is voiced by Dee Bradley Baker."
Source: Wikipedia, "Characters_of_Final_Fantasy_X_and_X-2", available under the CC-BY-SA License.