Fight your Friends! is the second stage in The Battle Cats POP! event.
Overall this is an easy stage. First comes the peons: Doges, Snache, and Those Guys. and then a few Hippos will come, after you start attacking the base a Mooth will come out. There's only one Mooth, so it should be easy after that.
Start by spawning a few cheap units at a time (around 2-3 is good) because the Mooth won't come out of the enemy's base until you hit it. Once one of your cheap cats die spawn another one, but keep on upgrading Worker Cat. Now if you have an expensive Uber Rare or a good unit that's expensive save up and then buy it! And then go full out on spawning other units and then hopefully win!