Stealing never annoyed me as much in this game than in IV and VI. I mainly use steal from regular enemies. It doesn't make sense that Locke and Edge struggle to steal from some random encounter monster. IX's thief doesn't struggle really at all with regular enemies and the only boss I found a pain to steal from was Hidegigas.

Also Bob didn't those cactuars have a tendency to run a lot from you, or are those the cactuars from X that act like that