A large wave of Wall Doges and a few Metal Doges start the stage. H. Nah and more Metal Doges will continue to spawn fairly quickly a short while later, and will continue to do so throughout the stage.
This level can be a massive pain unless you come prepared.
Strategy 1: 1-3 star
Items: Rich Cat, Cat CPU.
When the first Metal Doges come out, summon a Dragon, Paris, and Space Cat, along with a couple more Paris. As you accumulate more money, summon Ururun, Bahamut, and the uber.
You should have Cat CPU turned on by now to constantly summon your meat shields. This will keep the H. Nah and Metal Doges off your other units. After a while, you should have won. Take a minute to do a victory dance. This is one hellish ordeal of a level.
Strategy 2: 4-star (Siluman Tomcat)
Items: Rich Cat never hurts, but the Goemon Cats make it unnecessary.
Kill the Wall Doges with the Goemon Cats so you can send out your 3 heavy hitters, and just spam meatshields, Mochi Cats, and Paris Cats until you slowly win. The usage of Mochi Cat rather than a critical hitter and Goemon Cat for the beginning money is what makes the strategy really ingenious.