Growing Up (Expert) is the first stage in Adult Cat Awakes!.
Start the level. All that will spawn are Doge Darks in 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.
Begin the battle. Drop a few Erasers to stall the Doge Darks for a while.
Note:this only works if your Erasers has a TON of plus levels.
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, Prisoner Cat will spawn with a Rain D. Prisoner Cat has very slow movement, but all the other enemies move faster.
Let the Rain D and Metal Doges get close to your base, then use long-Rangers to destroy them. By the time they're all dead, Prisoner Cat should be near the base. Use close-ranged cats 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 long-Rangers should be able to hit Rain D while not getting killed by Prisoner Cat.
Once you kill the second Rain D, continue to kill Prisoner Cat with close-Rangers. Eventually, you should win.
Do note that a third Rain D. will also spawn if you take too long.