Mighty Morphin Power Rangers
In the first season of Power Rangers, the Sixth Ranger is the Green Dragon Ranger, Tommy Oliver (Jason David Frank). Tommy is a new student at Angel Grove High, and he entered a martial arts tournament that Jason was in. The two fought, Tommy showing that his fighting skills were equivalent of Jason's. This caught the attention both Kimberly, the Pink Ranger and Rita Repulsa. Rita captured him and, using the special Green Ranger powers she possessed, cast an evil spell over him, turning him into the Green Dragon Ranger.
In his first encounter with the Rangers, he defeats them easily. After continued attempts of trying to get to the Tommy underneath the ranger, and succeed. Jason destroyed the Sword of Darkness, the source of the evil spell over Tommy, allowing him to join up with the other rangers, becoming the first ever Sixth Ranger.
After Rita's continuous streak of losses against the Power Rangers with the help of Tommy, she set out to get back the Green Ranger powers she believed were hers. Using a special green candle, she slowly drained the Ranger powers from Tommy. Jason tried to enter the Dark Dimension where it was held, as well as where Tommy was being held prisoner, but he couldn't get there because of the relentless monster attacks by Rita. As Tommy's powers faded, he transferred the Dragon Powers to Jason to keep Rita from getting her hands on them.
He left the rangers for a short time, but came back after Rita kidnapped the parents of every student at Angel Grove High. He still had the Dragon Power Coin and morphed, knowing that each time he morphed it would weaken him. Zordon granted him a temporary power boost so he could continue to morph. But, Lord Zedd ultimately destroyed his powers, permanently.
Tommy spent awhile away from the Rangers, but after Zedd unleashed his Nimrod monster, Alpha 5 and Zordon knew it was time to make a new Ranger. They made Tommy the new White Ranger, a ranger whose powers couldn't be used for evil. He wielded his talking sword, Saba to summon the White Tigerzord.
Mighty Morphin Alien Rangers
Power Rangers: Wild Force
Power Rangers: Dino Thunder
Power Rangers: SPD
Sam was originally a lonely boy with no friends, who couldn't fit in the other kids. As result he was constantly bullied and made fun of for being different. Sam had the genetic ability to teleport objects as well as create illusions, something the other kids teased him for. Though he was misled into joining the Troobians, he rewrote his wrongs and joined S.P.D as a young cadet. 20 years later, Sam would grow into the S.P.D Omega Ranger, travelling back in time to assist the S.P.D with their crisis in hopes of changing the future. As a boy he was eagerly excited to become a power ranger and as an adult he had developed an optimistic outlook, following orders without question and using his brain more than the rest of his team. Being the Omega Ranger, Sam wears a wrist-mounted Omega Morpher, a highly advanced futuristic S.P.D technology. He also pilots the Omegamax Cycle which can transform into the Omegamax Megazord.
Power Rangers: Mystic Force
Udonna was once a powerful sorceress, the loyal wife of Leanbow and mother of Bowen. After the Great Battle of Good and Evil, she lost her husband and son, spending the next several years alone with her niece Claire. When dark magic arose she chose five teenagers to fulfil their destinies of becoming the Mystic Force. Udonna became the White Mystic Force Power Ranger wielding her mighty Snow Staff into battle. Though she lost her Snow Staff to Koragg near the beginning of the season, she would later reclaim her artifact, becoming the powerful sorceress she once was. She would later reunite with her lost husband Leanbow (Koragg) and her son Bowen (Nick Russell) after many years of separation from them and become a family once again. Udonna is a caring and wise mentor to the Mystic Force during the first arc.
Power Rangers: Jungle Fury