This enemy attacks very quickly and has insane movement speed, health and attack power. It also increases its already high attack power by 50% when under 50% health. Be sure to stack long-ranged Anti-Black Cats that can help you to deal with this gargantuan beast.
Luckily, two or more Bombercats are enough to permafreeze Razorback. The number can be reduced to one if you have freeze up (M) or 2 (S) combos. However, timing Bomber Cat on Taste of Success is crucial. The inclusion of Tackies tend to kill your Bomber cats before they even reach the frontline to freeze Razorback.
If you don't have Bombercat, Razorback is still beatable. Units such as Rodeo Cat, Pizza Cat (Talented works even better), and Thaumaturge can reduce Razorback's pushing power, giving you more time to defeat him.