Go, Go, Loser Ranger anime

Thirteen years ago, the Army of Evil attempted to invade Earth. They were confronted by the Super Sentai squadron of the Divine Dragon Rangers, also known as the Dragon Guardians, and their superweapons, the Divine Tools.

The evil army was, however, defeated within a year, all of its leaders wiped out, and the surviving (and nearly immortal) foot soldiers have been forced to reenact their defeat by the Guardians in front of crowds of spectators every Sunday ever since.

Tired of this charade and realizing that it was nothing more than slavery, one of the foot soldiers rebelled and decided to defeat the Dragon Guardians.