This enemy has massive health, high DPS and non-stop Area Attacks. Its only weaknesses are its somewhat low range and movement speed, lower than Cat even, so try to use those to your advantage in order to beat it.
In its debut stage, the best strategy is to stack Bahamut Cat at the beginning of the level. Units like Paris Cat will help greatly against it. Using Sniper the Cat is also recommended to keep it at bay if you are struggling. Otherwise, you can also use Sniper the Recruit instead if you have it.
In later stages you encounter him in, you should have a good deal of anti-Traitless units at your disposal, so using those will help to defeating it. However, Supercat will not work as he gets himself outranged.