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.