Before joining New Cooper's Gang, Ludwig wasn't exactly a gentleman.

Being humiliated in his younger years for being a iguana/lynx hybrid, he turned into a crazy psycho who wanted revenge against the World that had always treatened him like a "filthy monster".
However, as an "enfant prodige" he was very smart: he finished University at seven years old, and here he's 28 years old.

To defeat him, Diego (Sly and Carmelita's son) had to ask help to the Old Cooper Gang, especially Penelope's one. Infact, Ludwig does not hit ladies, he never did and he never will. But his muscular body and his brain ("I'm World's Greatest Mind!" -Ludwig) made of him a fearsome opponent: they didn't defeated him in a combat, but in a "tactic" fight. He was impressed by Penelope's intelligence and decided to join the New Cooper Gang, with Diego. Later, his sister joins too.

The battle would have been with him playing his organ. Yup, he can use it as a weapon.

Sly Cooper © SuckerPunch
Ludwig Lousteau © me