The Battle in Tokyo Against Orochimon

The Battle in Tokyo Against Orochimon (東京決戦 オロチモン, Tōkyō Kessen Orochimon) is the seventeenth episode of Digimon Adventure:

Summary
Just when Taichi and his friends thought they had finally defeated the enemy in the fake Tokyo, a new enemy appeared. The children work together with their Digimon to take down the eight-headed Ultimate Digimon.