Pound for pound is based on opinion. Raheem outboxed Morales somewhat easily. You won't find anybody arguing that Raheem would have outboxed the Castillo that gave Floyd trouble.
At 135, Morales would have nothing for Castillo. Not enough power or speed, and too easy to hit. Castillo would have Kayoed Morales.
JLC would've kicked his ass, EM didn't look all that great against an injured Jesus Chaves, when he moved up in weight, I just don't see him taking out a peak Castillo.
What a ****ing fight this would be. I see castillos body punching being the difference in this fight. He would cut the ring off on em and wear him down to the body possibly stopping him late. People are forgetting that Castillo was a big strong lw he would dwarf em in the ring on fight night.