Kaizoku Sentai Gokaiger

A group of young pirates from space come to Earth to obtain the "Greatest Treasure in the Universe", which can only be acquired after obtaining the Ultimate Powers of the 34 Super Sentai. However, they end up running afoul of the Space Empire Zangyack, whose earlier invasion forces were wiped out by the 34 Super Sentai long ago. As a result, the space pirates use "pirate copies" of the powers of the older teams and fight the Zangyack forces as the Gokaigers.

Keywords: monster, treasure hunt, superhero, giant robot, giant monster