Also, it depends on what part of disk two you're on.

Earlier parts lower the percentage of chance by which you can obtain a green/blue/black/gold chocobo through breeding.

If you've just gotten Cloud back on your team, you'll probably have a hard time getting anything. Unfortunately, the only time the percentage skyrockets is on disk 3 when you pretty much don't need any of them anymore.

If you're past the sub, you're chances are still fairly weak. Past the rocket, I'd say 38%. Past City of the Ancients . . . probably 50-50. Past Diamond, I think 70%.