Complex sentence: They are chased by Jean Claude who pilots the Robosnail robot (He resembles Mothra in Godzilla,) (picking Kimi up on the way), Reptar's nemesis, until they fight on a bridge and Chuckie knocks Robosnail into the Seine river.
Split into simpler sentences: They are chased by Jean Claude who pilots Reptar's nemesis, the Robosnail robot. The chase culminates in a fight on a bridge and Chuckie knocks Robosnail into the Seine river.