Complex sentence: He discovers that the Kaijus are not wild beasts but cloned living weapons that share a hive mind and fight at the behest of a race of alien colonists who wish to invade Earth.
Split into simpler sentences: He discovers that the Kaijus are not wild beasts but are cloned living weapons that share a hive mind. The Kaiju fight at the behest of a race of alien colonists who wish to invade Earth.