Complex sentence: Eggman, realizing its potential, uses it to go back in time and team up with his past ("Classic") self, and the two convert it to a robot to erase their past defeats from history.
Split into simpler sentences: Eggman, realizing its potential, uses it to go back in time and team up with his past ("Classic") self. The two convert it to a robot to erase their past defeats from history.