Angry Sun is a metal enemy, so use fast critical hitters like Catornado, Jurassic Cat or, better, Crazed Moneko to defeat it as soon as possible, as to avoid dealing with him and more than one Cow Doge at once. The Cow Doges can be easily defeated with Rusher units, most preferably Awakened Bahamut Cat; who, at level 30, can one-shot every enemy consistently. However, on Level 10, the Cow Doges can actually survive from a level 30 Awakened Bahamut's first hit.
To stall the enemies, bring many meatshields and/or a good staller for traitless (Suntan, Healer Cat CC etc.). Zamboney Cat is also useful, but gets shredded too quickly in the last stages.
When it comes to attackers, Teacher BearCat shines the most, but it is easy enough to win by just stacking any midranger with area attack, such as Cameraman, as long as they don't cost too much.
A good strategy that will easily beat Level 10 is equip 7-8 spammable cheap meatshields, and Awakened Bahamut Cat. Cat CPU and Rich Cat are recommended. When you enter battle, save up around 4500 cents. Spam a bit of meatshields so Bahamut doesn't rush forward and die, then buy Awakened Bahamut. Turn on CPU, and sit back while your meatshields shred through Angry Sun.
Trivia[]
The base states that there is a gift of Cat Food, despite it only being given if all the stages are cleared.