Sonic Underground (1999)

S1E36 Sleepers

While on a mission in a remote area of Robotropolis, the Hedgehogs receive alarming news about the disappearance of several freedom fighters who are on the verge of being roboticized. Sonic speeds off to rescue his friends, but unfortunately, he arrives too late. He finds that the entire group of freedom fighters has already been roboticized, and among them is Cyrus' father.