Karsh is first seen with Sugar and Salton, the two bumbling idiots (the Biggs and Wedge of Chrono Cross, maybe?), and is also the first real boss you'll fight. He is one tough guy, and one of his attacks is to call his pet dinosaur and charge at you. Karsh has some kind of history with Grenn, Ridel and Dario, which actually plays a significant part in the story.
You just gotta love non-linearity. You might or might not meet this guy early on, depending on what path you choose. Fret not, you'll still meet him later on, but he'll have additional help. I don't know whether to describe this guy as incredibly smart or incredibly stupid, as he only protects his head and leaves his whole body open.
This is the only person in this list who is not under Jyakotu's employ. This guy is tough, and you probably know that just by looking at him. One of his special techniques involves using his ultra-funky hair to generate a laser that can hurt everyone. Also, if you take a close look at his left arm, it's actually mechanical. Another one of his attacks is detaching this arm and firing it at one person. No, I'm not kidding!