He's the biggest of the watchdogs and is likely the only one aside from Commander Peepers to have muscles.
From what we can tell, Moose is very tough and might've been annoyed with Westley's personality. He is also very smug, even to Lord Hater as seen in "The Rager", where he wouldn't even let his own boss into the prison party.
Powers and Abilities
He can punch really hard, as proven when he punched Westley in "The Little Guy".
In "The Little Guy", when Westley was trying to get the other watchdogs to wake up, he came back to wake up Moose. Probably due to Westley's annoying personality, Moose punched him in the face.