Which king of Judah defeated Edom and challenged Israel to battle?

Answer: Amaziah

Amaziah defeated Edom and then sent messengers to challenge Israel's king.

“Amaziah struck down 10,000 Edomites in the Valley of Salt. He took Sela in battle and called it Joktheel, which is its name to this very day. Then Amaziah sent messengers to the king of Israel Jehoash son of Jehoahaz, the son of Jehu. “Come, let us meet face to face,” he said.”— 2 Kings 14:7-8 (BSB)