I can't think of anyone who can really beat Thrawn. Someone out there could give him a challenge, but he could outwit anyone. He can make something out of nothing. You would have to pit him against a Galactic Government in order to have a good match-up, and we saw what happened when he went up against the New Republic. If it weren't for the Noghri, Thrawn would have swept the New Republic aside.
Perhaps. But I'm sure theere is SOMEBODY out there who can give him a run for his money. Besides, it'd be a shame to neglect giving a Kaggath to Thrawn because he's awesome. That's flawed reasoning. He should get a Kaggath because he is awesome!
If there's no one who can match him then could we consider paring up two lesser forces against him? Thrawn will get a Kaggath one way or another.