Complex sentence: Both teams go on to defeat the Crime and Black Cross armies and the Big Four combine to form the super cyborg "Big Four Robo" who overwhelms both teams until Big One arrives and the two teams combine their attacks to destroy it.
Split into simpler sentences: Both teams go on to defeat the Crime and Black Cross armies. The Big Four combine to form the super cyborg "Big Four Robo", who overwhelms both teams until Big One arrives and the two teams combine their attacks to destroy it.