Zelkova Strikes Back

"Zelkova Strikes Back" or "The True Form of the Metarex!?" (メタレックスの正体！？) is the 72nd episode of Sonic X

Plot
The Blue Typhoon arrives at a planet, but Yellow Zelkova attacks the Blue Typhoon, equipped with a special energy shield built by Dr. Eggman. Sonic attempts to stop him, but is unable to break through the shield. Picking up where they left off, Zelkova and Knuckles get into a fierce battle, during which Knuckles smashes Zelkova's knee and breaks the spikes on one of his gloves. Using a cable from the Blue Typhoon, Sonic and the others channel lightning to overload Zelkova's shield. Zelkova's mechanical outer body is destroyed, revealing his flesh form beneath. Zelkova attacks, but is knocked into a nearby lava pit by Knuckles. Pale Bay Leaf informs Eggman of Zelkova's demise, mocking the failure of his shield. Shadow and Rouge find a fake Chaos Emerald at the top of the tree, but they hear groaning from its base. They find Leon (from the Resistance in Episode 68) being consumed by the tree, saying that the Metarex betrayed them. He also gives Shadow a memory chip and says it's not too late to destroy the Metarex.

Trivia

 * Extra scene: In the Japanese Version Knuckles try to help Yellow Zelkova from lava pit, but Yellow Zelkova refuse to help and he accepts his death with his own.