Growing Up (Expert) is the first stage in Adult Cat Awakes!
Starting the level, all that will spawn are some Doge Darks at a slow rate.
Shortly after hitting the base Duche will start coming out of it.
Later on, another Rain D. will spawn, and more Metal Doges will spawn in groups of two.
Beginning the battle spawn a Erasers to stall the Doge Darks for a while, use other meatshields if they are pushing to hard. When you get to max money, begin to use a few cats. Enough that you get to the base, but not so much that they don't die. When you attack the base, let the Rain D. and Metal Doges get close to your base, then use Rangers to destroy them. By the time they're all dead, Prisoner Cat should be near the base. Use All-Rounders or Rushers like Jamiera, Crazed Titan, and Awakened Bahamut to hit Prisoner Cat. Also spawn meatshields, Island, and Crazed Whale for the Metal Doges. After a while, the second Rain D. should spawn. Stall with meatshields, and your Rangers should be able to hit Rain D while not getting killed by Prisoner Cat. Once you kill the second Rain D, continue to chip down Prisoner Cat with All-Rounders or Rushers. Eventually, Prisoner Cat will die and you should win, but do note that a third Rain D. will also spawn if you take too long.