How do you unlock wish cave in blue rescue team?

After you beat the story line have the friend area sky blue plains (also the friend area Mt. Moonview if you plan on catching Jirachi while you are there) talk to Ekans and answer his mission about Medicham and you'll unlock the cave. You'll have to rescue her first, then you can go back and face Jirachi. It's 99 floors, temporarily resets you to level 1 and will get rid of any money you are carrying. Be prepared!