Complex sentence: Eggman attacks her with his mecha, and Tails defends her; she then spends much of the remaining game searching for Chaos Emeralds with Tails and Knuckles.
Split into simpler sentences: Eggman attacks her with his mecha, but Tails defends her. Amy then spends much of the remaining game searching for Chaos Emeralds with Tails and Knuckles.