What kind of animal did God require for the Passover lamb?

Answer: An unblemished year-old male

The lamb had to be an unblemished year-old male (KJV: "without blemish, a male of the first year"), from the sheep or goats.

“Your lamb must be an unblemished year-old male, and you may take it from the sheep or the goats.”— Exodus 12:5 (BSB)