Kaizoku Sentai Gokaiger

From the introduction:

~Super Hero Getter~

The showboat pirates of Gokaiger

Space Empire Zangyack, a powerful interstellar empire, made of all manner of alien forces have conquered many planets. Just days after the Goseiger’s victory over their final foe, countless Zangyack battleships came to earth bombarding human cities. Hundreds of gormin troops led by Sugormin commanders fought on the ground. How long the war lasted is unknown, what is known is that before the final confrontation a battle between hundreds of mecha and the Zangyack fleet occurred. Many of the mecha were destroyed during this battle.