Cheat: Unlimited Battle Energy (called CP in game).
Need: Root access and ES File Explorer
What to do: Go to data\data\jp.kiteretsu.zookeeperbattle.google and open file zk.dat as text.
Then find arguement zk_cp and change the value to 6. Exit and save the file. Exit and reenter the folder and delete the zk.dat.bak file.
Do this every time you are out of battle energy.