A lot of Gorys will be spawned after your cats hit the enemy's base. They will act as a support to Mooth, the stage's boss.
For all chapters - When the battle begins, start upgrading your Cat Wallet to max level, when enemies will get close to your base, send out few Tank Cats/Wall Cats. Don't get scared when Squire Rel dashes towards you, after all she can easily be killed by a Cat Cannon/Meatshields. The time will come when your money will be maxed out; that's when you can send out all of your basic cats. When they will start to hit the enemy's base, start spawning Gross Cats/Sexy Legs Cats and Bird Cats/Ufo Cats. This will be enough to kill all of those Gorys. Now for the main problem - Mooth. All those dead Gorys will give you a lot of money. Spend that money wisely, by buying Lizard Cats/Dragon Cats and Titan Cats/Mythical Titan Cats.