Once a Ranger

"Once a Ranger" is a special two-part team-up episode of Power Rangers: Operation Overdrive, commemorating the fifteenth season of the popular Power Rangers children's television series begun in 1993. It features the return of five former Rangers who aid the current team of Operation Overdrive Rangers against the son of the original two villains of the series.

Plot
Thrax, the son of Rita Repulsa and Lord Zedd arrives and proposes a temporary alliance with the four factions of Operation Overdrive villains. The villains, hesitant at first, join forces and wage an all out war against the Rangers. United, the villains defeat the Rangers. Then, as the final attack, Thrax severs their link to the Morphing Grid, stripping them of their powers. Sentinel Knight's spirit arrives and whisks the Rangers to safety, then he calls upon Adam Park, Tori Hanson, Kira Ford, Bridge Carson, and Xander Bly to replace the current Ranger team. The Overdrive Rangers feel left out and decide to leave Operation Overdrive to return to their normal lives to before they became Rangers. Adam leaves with the other previous Rangers to bring Alpha 6 to repair the Operation Overdrive link to the Morphing Grid. Meanwhile, Mack learns of the legend of Excelsior -- a sword which is the only weapon that can fully destroy the Sentinel Knight -- and goes to retrieve it. When Rose intuits what Mack is doing, she gathers the rest of the Overdrive team to follow (which wasn't hard, as none of the Overdrive Rangers were happy with civilian life). Successfully retrieving the sword from beneath Thrax's fingertips results in a climactic final battle between the current and retro Rangers and their enemies. The Sentinel Knight, restored to full power thanks to Excelsior, joins them.

Returning Power Rangers
Five former Rangers return for the episode:
 * Adam Park: The second Black Ranger of Mighty Morphin Power Rangers, portrayed by Johnny Yong Bosch. Adam uses his Battle Axe and the Defender Vest.
 * Tori Hanson: The Blue Wind Ranger of Power Rangers: Ninja Storm, portrayed by Sally Martin.
 * Kira Ford: The Yellow Dino Ranger of Power Rangers: Dino Thunder, portrayed by Emma Lahana.
 * Bridge Carson: The S.P.D. Red Ranger of Power Rangers: S.P.D., portrayed by Matt Austin. Bridge was promoted to Blue Ranger at the end of Power Rangers S.P.D. In a future story arc, Fowler Birdie would retire as Supreme Commander of Space Patrol Delta. Doggie Cruger would take over his position, prompting a promotion for Sky Tate (who had been promoted to Red Ranger at the end of the S.P.D. season). It is assumed that Sky took over Cruger's position.
 * Xander Bly: The Green Mystic Ranger of Power Rangers: Mystic Force, portrayed by Richard Brancatisano.