Complex sentence: To battle him, The One gave Primus this power also, but Primus opted to remain in planet mode, and passed the transforming abilities on to thirteen robots that he created from himself; the first Transformers.
Split into simpler sentences: To battle him, The One gives Primus this power as well, but Primus opts to remain in planet mode. He passes the transforming abilities on to thirteen robots he creates, the first Transformers.